81_FR_52950 81 FR 52796 - Endangered and Threatened Wildlife and Plants; Endangered Species Status for Texas Hornshell

81 FR 52796 - Endangered and Threatened Wildlife and Plants; Endangered Species Status for Texas Hornshell

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service

Federal Register Volume 81, Issue 154 (August 10, 2016)

Page Range52796-52809
FR Document2016-18816

We, the U.S. Fish and Wildlife Service (Service), propose to list the Texas hornshell (Popenaias popeii), a freshwater mussel species from New Mexico and Texas, as an endangered species under the Endangered Species Act (Act). If we finalize this rulemaking as proposed, it would extend the Act's protections to this species.

Federal Register, Volume 81 Issue 154 (Wednesday, August 10, 2016)
[Federal Register Volume 81, Number 154 (Wednesday, August 10, 2016)]
[Proposed Rules]
[Pages 52796-52809]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2016-18816]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2016-0077; 4500030113]
RIN 1018-BB34


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for Texas Hornshell

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
list the Texas hornshell (Popenaias popeii), a freshwater mussel 
species from New Mexico and Texas, as an endangered species under the 
Endangered Species Act (Act). If we finalize this rulemaking as 
proposed, it would extend the Act's protections to this species.

DATES: We will accept comments received or postmarked on or before 
October 11, 2016. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for 
public hearings, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by September 26, 2016.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter FWS-R2-ES-2016-0077, 
which is the docket number for this rulemaking. Then, in the Search 
panel on the left side of the screen, under the Document Type heading, 
click on the Proposed Rules link to locate this document. You may 
submit a comment by clicking on ``Comment Now!''
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R2-ES-2016-0077, U.S. Fish and Wildlife 
Service, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on http://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Public Comments, below, for more information).

FOR FURTHER INFORMATION CONTACT: Chuck Ardizzone, U.S. Fish and 
Wildlife Service, Texas Coastal Ecological Services Field Office, 17629 
El Camino Real #211, Houston, TX 77058; by telephone 281-286-8282; or 
by facsimile 281-488-5882. Persons who use a telecommunications device 
for the deaf (TDD) may call the Federal Information Relay Service 
(FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Act, if a species is 
determined to be an endangered or threatened species throughout all or 
a significant portion of its range, we are required to promptly publish 
a proposal in the Federal Register and make a determination on our 
proposal within 1 year. Critical habitat shall be designated, to the 
maximum extent prudent and determinable, for any species determined to 
be an endangered or threatened species under the Act. Listing a species 
as an endangered or threatened species and designations and revisions 
of critical habitat can only be completed by issuing a rule.
    This rulemaking proposes the listing of the Texas hornshell 
(Popenaias popeii) as an endangered species. The Texas hornshell is a 
candidate species for which we have on file sufficient information on 
biological vulnerability and threats to support preparation of a 
listing proposal, but for which development of a listing regulation has 
been precluded by other higher priority listing activities. This 
proposed rule reassesses all available information regarding the status 
of and threats to the Texas hornshell.
    The basis for our action. Under the Act, we can determine that a 
species is an endangered or threatened species based on any of five 
factors, acting alone or in combination: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence. We have determined that the Texas 
hornshell is in danger of extinction due to habitat loss from loss of 
water flow, decreased water quality, and increased accumulation of fine 
sediments (Factor A) and predation (Factor C).
    We will seek peer review. We will seek comments from independent 
specialists to ensure that our determination is based on scientifically 
sound data, assumptions, and analyses. We will invite these peer 
reviewers to comment on our listing proposal. Because we will consider 
all comments and information we receive during the comment period, our 
final determination may differ from this proposal.
    We prepared a species status assessment report (SSA report) for the 
Texas hornshell. The SSA report documents the results of the 
comprehensive biological status review for the Texas hornshell and 
provides an account of the species' overall viability through 
forecasting of the species' condition in the future (Service 2016, 
entire). We received feedback from four scientists with expertise in 
freshwater mussel biology, ecology, and genetics as peer review of the 
SSA report. The reviewers were generally supportive of our approach and 
made suggestions and comments that strengthened our analysis. The SSA 
report and other materials relating to this proposal can be found at 
http://www.regulations.gov under Docket No. FWS-R2-ES-2016-0077.

Information Requested

Public Comments

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned governmental agencies, 
Native American tribes, the scientific community, industry, or any 
other interested parties concerning this proposed rule. We particularly 
seek comments concerning:

[[Page 52797]]

    (1) The Texas hornshell's biology, range, and population trends, 
including:
    (a) Biological or ecological requirements of the species, including 
habitat requirements for feeding and spawning;
    (b) Genetics and taxonomy;
    (c) Historical and current range, including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the species, its 
habitat, or both.
    (2) Factors that may affect the continued existence of the species, 
which may include habitat modification or destruction, overutilization, 
disease, predation, the inadequacy of existing regulatory mechanisms, 
or other natural or manmade factors.
    (3) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to this species and existing regulations 
that may be addressing those threats.
    (4) Additional information concerning the historical and current 
status, range, distribution, and population size of this species, 
including the locations of any additional populations of this species, 
particularly in Mexico.
    (5) Information related to climate change within the range of the 
Texas hornshell and how it may affect the species' habitat.
    (6) The reasons why areas should or should not be designated as 
critical habitat as provided by section 4 of the Act (16 U.S.C. 1531 et 
seq.)
    (7) Specific information on:
    (a) The amount and distribution of habitat for the Texas hornshell;
    (b) What areas, that are currently occupied and that contain the 
physical and biological features essential to the conservation of the 
Texas hornshell, should be included in a critical habitat designation 
and why;
    (c) Special management considerations or protection that may be 
needed for the essential features in potential critical habitat areas, 
including managing for the potential effects of climate change; and
    (d) What areas not occupied at the time of listing are essential 
for the conservation of the species and why.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is an endangered or threatened 
species must be made ``solely on the basis of the best scientific and 
commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in ADDRESSES. We request that you 
send comments only by the methods described in ADDRESSES.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the Web site. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on http://www.regulations.gov.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on http://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Texas Coastal Ecological Services Field Office (see 
FOR FURTHER INFORMATION CONTACT).

Public Hearing

    Section 4(b)(5) of the Act provides for one or more public hearings 
on this proposal, if requested. Requests must be received within 45 
days after the date of publication of this proposed rule in the Federal 
Register (see DATES, above). Such requests must be sent to the address 
shown in FOR FURTHER INFORMATION CONTACT. We will schedule public 
hearings on this proposal, if any are requested, and announce the 
dates, times, and places of those hearings, as well as how to obtain 
reasonable accommodations, in the Federal Register and local newspapers 
at least 15 days before the hearing.

Peer Review

    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), we will seek the expert 
opinions of five appropriate and independent specialists regarding this 
proposed rule. The purpose of peer review is to ensure that our listing 
determination is based on scientifically sound data, assumptions, and 
analyses. We invite comment from the peer reviewers during the public 
comment period on this proposed rule.

Previous Federal Actions

    We identified the Texas hornshell as a Category 2 candidate species 
in our January 6, 1989, Review of Vertebrate Wildlife (54 FR 554). 
Category 2 candidates were defined as species for which we had 
information that proposed listing was possibly appropriate, but 
conclusive data on biological vulnerability and threats were not 
available to support a proposed rule at the time. The species remained 
a Category 2 candidate in subsequent annual candidate notices of review 
(CNOR) (56 FR 58804, November 21, 1991, and 59 FR 58982, November 15, 
1994). In the February 28, 1996, CNOR (61 FR 7596), we discontinued the 
designation of Category 2 species as candidates; therefore, the Texas 
hornshell was no longer a candidate species.
    Subsequently, in 2001, the Texas hornshell was added to the 
candidate list (66 FR 54808, October 30, 2001). Candidates are those 
fish, wildlife, and plants for which we have on file sufficient 
information on biological vulnerability and threats to support 
preparation of a listing proposal, but for which development of a 
listing rule is precluded by other higher priority listing activities. 
The Texas hornshell was included in all of our subsequent annual CNORs 
(67 FR 40657, June 13, 2002; 69 FR 24876, May 4, 2004; 70 FR 24870, May 
11, 2005; 71 FR 53756, September 12, 2006; 72 FR 69034, December 6, 
2007; 73 FR 75176, December 10, 2008; 74 FR 57804, November 9, 2009; 75 
FR 69222, November 10, 2010; 76 FR 66370, October 26, 2011; 77 FR 
69994, November 21, 2012; 78 FR 70104; November 22, 2013; 79 FR 72450, 
December 5, 2014; and 80 FR 80584, December 24, 2015). On May 11, 2004, 
we were petitioned to list the Texas hornshell, although no new 
information was provided in the petition. Because we had already found 
the species warranted listing, no further action was taken on the 
petition.
    On September 9, 2011, the Service entered into two settlement 
agreements regarding species on the candidate list at that time 
(Endangered Species Act Section 4 Deadline Litigation, No. 10-377 
(EGS), MDL Docket No. 2165 (D.D.C. May 10, 2011)). This proposed 
listing rule fulfills the requirements of those settlement agreements 
for the Texas hornshell.

Background

    A thorough review of the taxonomy, life history, ecology, and 
overall viability of the Texas hornshell

[[Page 52798]]

(Popenaias popeii) is presented in the Species Status Assessment Report 
for the Texas Hornshell (SSA report) (Service 2016; available at http://www.regulations.gov). The SSA report documents the results of the 
comprehensive biological status review for the Texas hornshell and 
provides an account of the species' overall viability through 
forecasting of the species' condition in the future (Service 2016, 
entire). In the SSA report, we summarized the relevant biological data 
and a description of past, present, and likely future stressors and 
conducted an analysis of the viability of the species. The SSA report 
provides the scientific basis that informs our regulatory decision 
regarding whether this species should be listed as an endangered or 
threatened species under the Act. This decision involves the 
application of standards within the Act, its implementing regulations, 
and Service policies (see Determination, below). The SSA report 
contains the risk analysis on which this determination is based, and 
the following discussion is a summary of the results and conclusions 
from the SSA report. We solicited peer review of the draft SSA report 
from five qualified experts. We received responses from four of the 
reviewers, and we modified the SSA report as appropriate.

Species Description

    The Texas hornshell is a medium sized (3 to 4 inches long) 
freshwater mussel with a dark brown to green, elongate, laterally 
compressed shell (Howells et al. 1996, p. 93; Carman 2007, p. 2). The 
Texas hornshell was described by Lea (1857, p. 102) from the Devils 
River in Texas and Rio Salado in Mexico. Currently, the Texas hornshell 
is classified in the unionid subfamily Ambleminae (Campbell et al. 
2005, pp. 140, 144) and is considered a valid taxon by the scientific 
community (Turgeon et al. 1998, p. 36).
    Freshwater mussels, including the Texas hornshell, have a complex 
life history. Males release sperm into the water column, which are 
taken in by the female through the incurrent siphon (the tubular 
structure used to draw water into the body of the mussel). The sperm 
fertilizes the eggs, which are held during maturation in an area of the 
gills called the marsupial chamber. The developing larvae remain in the 
gill chamber until they mature and are ready for release. These mature 
larvae, called glochidia, are obligate parasites (cannot live 
independently of their hosts) on the gills, head, or fins of fishes 
(Vaughn and Taylor 1999, p. 913). Glochidia die if they fail to find a 
host fish, attach to a fish that has developed immunity from prior 
infestations, or attach to the wrong location on a host fish (Neves 
1991, p. 254; Bogan 1993, p. 599). Glochidia encyst (enclose in a cyst-
like structure) on the host's tissue, draw nutrients from the fish, and 
develop into juvenile mussels weeks or months after attachment (Arey 
1932, pp. 214-215).
    For the Texas hornshell, spawning generally occurs from March 
through August (Smith et al. 2003, p. 335), and fertilized eggs are 
held in the marsupial chambers of females for 4 to 6 weeks (Smith et 
al. 2003, p. 337). Glochidia are released in a sticky mucous net or 
string (Carman 2007, p. 9); the host fish likely swim into the nets, 
and the glochidia generally attach to the face or gills of the fish and 
become encysted in its tissue (Levine et al. 2012, pp. 1858). The 
glochidia will remain encysted for about a month through transformation 
to the juvenile stage. Once transformed, the juveniles will excyst from 
the fish and drop to the substrate. The known primary host fishes for 
the Texas hornshell are river carpsucker (Carpiodes carpio), grey 
redhorse (Moxostoma congestum), and red shiner (Cyprinella lutrensis) 
(Levine et al. 2012, pp. 1857-1858).
    Mussels are generally immobile but experience their primary 
opportunity for dispersal and movement within the stream as glochidia 
attached to a mobile host fish (Smith 1985, p. 105). Upon release from 
the host, newly transformed juveniles drop to the substrate on the 
bottom of the stream. Those juveniles that drop in unsuitable 
substrates die because their immobility prevents them from relocating 
to more favorable habitat. Juvenile freshwater mussels burrow into 
interstitial substrates and grow to a larger size that is less 
susceptible to predation and displacement from high flow events (Yeager 
et al. 1994, p. 220). Throughout the rest of their life cycle, mussels 
generally remain within the same small area where they excysted from 
the host fish.
    Life span is not known for the Texas hornshell, although two adult 
individuals were captured and marked in the Black River in New Mexico 
in 1997, and were recaptured 15 years later (Inoue et al. 2014, p. 5). 
Species in the subfamily Ambleminae, which includes Texas hornshell, 
commonly live more than 20 years (Carman 2007, p. 9), so we assume the 
Texas hornshell can live at least 20 years.
    Little is known about the specific feeding habits of Texas 
hornshell. Like all adult freshwater mussels, Texas hornshell are 
filter feeders, siphoning suspended phytoplankton and detritus from the 
water column (Yeager et al. 1994, p. 221; Carman 2007, p. 8).

Habitat and Range

    Adult Texas hornshell occur in medium to large rivers, in habitat 
not typical for most mussel species: In crevices, undercut riverbanks, 
travertine shelves, and under large boulders adjacent to runs (Carman 
2007, p. 6; Randklev et al. 2015, p. 8), although in the Devils River, 
the species is found in gravel beds at the heads of riffles and rapids 
(Randklev et al. 2015, p. 8). Small-grained material, such as clay, 
silt, or sand, gathers in these crevices and provides suitable 
anchoring substrate. These crevices are considered to be flow refuges 
from the large flood events that occur regularly in the rivers this 
species occupies. Texas hornshell are able to use these flow refuges to 
avoid being swept away as large volumes of water move through the 
system, as there is relatively little particle movement in the flow 
refuges, even during flooding (Strayer 1999, p. 472). Texas hornshell 
are not known from lakes, ponds, or reservoirs.
    The Texas hornshell historically ranged throughout the Rio Grande 
drainage in the United States (New Mexico and Texas) and Mexico as well 
as Mexican Gulf Coast streams south to the northern Mexican state of 
Veracruz (Johnson 1999, p. 23). Currently, five known populations of 
Texas hornshell remain in the United States: Black River (Eddy County, 
New Mexico), Pecos River (Val Verde County, Texas), Devils River (Val 
Verde County, Texas), Lower Canyons of the Rio Grande (Brewster and 
Terrell Counties, Texas), and Lower Rio Grande near Laredo (Webb 
County, Texas) (Map 1). They are described briefly below.

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[GRAPHIC] [TIFF OMITTED] TP10AU16.000

    Black River: The Black River, in Eddy County, New Mexico, 
originates from several groundwater-fed springs and flows approximately 
30 miles (mi) (48 kilometers (km)) through the Chihuahuan Desert until 
its confluence with the Pecos River (Inoue et al. 2014, p. 3) near 
Malaga, New Mexico. Extensive population monitoring (Lang 2001, entire; 
2006, entire; 2010, entire; 2011, entire) and a long-term mark-
recapture study (Inoue et al. 2014, entire) have yielded significant 
information about the population size and extent. Texas hornshell occur 
in approximately 8.7 mi (14.0 km) of the middle Black River, between 
two low-head (small) dams (Lang 2001, p. 20). The total population size 
has been estimated at approximately 48,000 individuals (95 percent 
confidence interval: 28,849-74,127) (Inoue et al. 2014, p. 7), with a 
diversity of size classes, primarily aggregated in flow refuges within 
narrow riffles. The population remained relatively stable over the 15 
year study period from 1997 to 2012 (Inoue et al. 2014, p. 6).
    Pecos River: In the Pecos River, inundation from Amistad Reservoir 
has resulted in the extirpation of Texas hornshell from the lower 
reaches of the river. Additionally, salinity levels are too high for 
freshwater mussel habitation in much of the Pecos River from the 
confluence with the Black River in New Mexico, downstream to the 
confluence with Independence Creek. However, three live Texas hornshell 
were collected from a small section of the Pecos River downstream of 
the confluence with Independence Creek and upstream of Amistad 
Reservoir near Pandale in Val Verde County, Texas, as well as 37 shells 
(Bosman et al. 2016, p. 6; Randklev et al. 2016, p. 9). Farther 
downstream, only dead shells were found in 2016, although they were 
numerous (Bosman et al. 2016, p. 6; Randklev et al. 2016, p. 9). Live 
individuals had not been collected at this location since 1973 
(Randklev et al. 2016, p. 4).
    Because the sample size of live individuals is so small (three live 
individuals found in recent months), it is difficult to draw many 
conclusions about the population. The population appears to be 
extremely small, and no evidence of reproduction was noted.
    Devils River: Texas hornshell were historically found in the Devils 
River and were known to occupy only the lower reaches of the river, 
which are currently inundated by Amistad Reservoir (Neck 1984, p. 11; 
Johnson 1999, p. 23; Burlakova and Karatayev 2014, p. 19). In recent 
years, 11 individuals were collected from upstream in the Devils River 
between 2008 and 2014 (Burlakova and Karatayev 2014, p. 16; Karatayev 
et al. 2015, p. 4). More intensive surveys conducted in 2014 and 2015, 
including 11 sites, have yielded 48 individuals at two sites: All from 
The Nature Conservancy's Dolan Falls Preserve except for a singleton at 
the Devils River State Natural Area's Dan A. Hughes Unit (formerly 
known as the Big Satan Unit) (Randklev et al. 2015, pp. 6-7). Because 
of the increased number of individuals collected in 2014 and 2105, it 
is likely that the Devils River population is more numerous than 
previously thought, although we do not expect that this

[[Page 52800]]

population is particularly large based on the limited number of 
collections to date. Interestingly, Texas hornshell in the Devils River 
occupy different habitats than those in the rest of the range; instead 
of being found under rock slabs and in travertine shelves, they occupy 
gravel beds at the heads of riffles or in clean-swept pools with 
bedrock (Randklev et al. 2015, p. 8). Even though the number of 
collected individuals is small, several young individuals were found, 
as well as females brooding glochidia (gravid females) (Randklev et al. 
2015, p. 8), indicating reproduction and recruitment (offspring survive 
to join the reproducing population) are occurring in the Devils River 
population.
    Rio Grande--Lower Canyons: One of two remaining populations of 
Texas hornshell in the Rio Grande is found in the Lower Canyons, just 
downstream of Big Bend National Park, in Terrell County, Texas. 
Burlakova and Karatayev (2014, p. 16) found the species in low density 
(approximately 40 individuals per km) in this region of the Rio Grande. 
Subsequent surveys by Randklev et al. (2015, entire) confirmed the 
presence of Texas hornshell in approximately 18.5 mi (30 km) of the 
Lower Canyons in two sections, finding that the species occupies 
approximately 63 percent of sites with suitable (rocky) habitat. For 
purposes of this analysis, we presume the entire section between these 
collections, approximately 62 mi (100 km), is occupied. Sites in the 
Rio Grande--Lower Canyons reach vary in density, with the densest sites 
near Sanderson Canyon, Terrell County, Texas, and decreasing downstream 
(Randklev et al. 2015, p. 13); the average density of Texas hornshell 
at each site is lower compared to the Black River and Rio Grande--
Laredo (5  14 individuals per site). Texas hornshell may 
occur between the known occupied sections, near the confluence with San 
Francisco Creek (Howells 2001a, p. 6), but limited access has prevented 
recent surveys from determining current occupancy of this reach. Young 
individuals and gravid females have been found throughout the Lower 
Canyons reach, indicating recruitment is occurring (Randklev et al. 
2015, p. 8).
    Rio Grande--Laredo: The largest Texas hornshell population occurs 
from Laredo, Texas (near La Bota Ranch just northwest of Laredo), 
upstream approximately 56 mi (90 km) (Randklev et al. 2015, p. 7). The 
density in this reach is high, with some habitat patches containing 
more than 8,000 individuals (Karatayev et al. 2015, p. 4) and 100 
percent of surveyed patches of suitable habitat containing Texas 
hornshell (Randklev et al. 2015, p. 7). Throughout this reach, the 
density of Texas hornshell is estimated 170  131 
individuals per suitable (rocky) habitat site (Randklev et al. 2015, p. 
7). Young individuals and gravid females have been found throughout the 
Laredo reach, indicating reproduction and recruitment are occurring 
(Randklev et al. 2015, p. 8). No live Texas hornshell have been found 
downstream of the city of Laredo in recent years.
    Mexico: A large portion of the Texas hornshell's estimated 
historical range is in Mexico. The species occurred in the Rio Salado 
basin, which is a tributary to the Rio Grande in Mexico, and in 
approximately 15 rivers that flow into the Gulf of Mexico. At one time, 
one-half to two-thirds of the species' range may have been in Mexico. 
Unfortunately, the most recent live collections of Texas hornshell in 
Mexico occurred in the 1980s (Mussel Project 2015, entire), and we have 
very few records of surveys with positive or negative collection data 
since that time. We have no information on population size or extent 
during those times of collection, and we also have no information on 
whether populations of Texas hornshell still occur in one or more of 
these streams; therefore, we have very low confidence in the species' 
current condition throughout most of the Mexican range. One or more of 
these populations may still be extant, or they may all be extirpated.

Species Needs

    Texas hornshell need seams of fine sediment in crevices, undercut 
riverbanks, travertine shelves, and large boulders in riverine 
ecosystems with flowing water and periodic cleansing flows to keep the 
substrate free of fine sediment accumulation. They need water quality 
parameters to be within a suitable range (i.e., dissolved oxygen above 
3 milligrams/liter (mg/L), salinity below 0.9 parts per thousand, and 
ammonia below 0.7 mg/L (Sparks and Strayer 1998, p. 132; Augspurger et 
al. 2003, p. 2574; Augspurger et al. 2007, p. 2025; Carman 2007, p. 6)) 
and phytoplankton as food. Finally, Texas hornshell need host fish to 
be present during times of spawning.
    We describe the Texas hornshell's viability by characterizing the 
status of the species in terms of its resiliency (ability of the 
populations to withstand stochastic events), redundancy (ability of the 
species to withstand large-scale, catastrophic events), and 
representation (the ability of the species to adapt to changing 
environmental conditions). Using various time frames and the current 
and projected resiliency, redundancy, and representation, we describe 
the species' level of viability over time. For the Texas hornshell to 
maintain viability, its populations or some portion thereof must be 
resilient. A number of factors influence the resiliency of Texas 
hornshell populations, including occupied stream length, abundance, and 
recruitment. Elements of Texas hornshell habitat that determine whether 
Texas hornshell populations can grow to maximize habitat occupancy 
influence those factors, thereby increasing the resiliency of 
populations. These resiliency factors and habitat elements are 
discussed here.
    Occupied Stream Length: Most freshwater mussels, including Texas 
hornshell, are found in aggregations, called mussel beds, that vary in 
size from about 50 to greater than 5,000 square meters (m\2\) (540 to 
greater than 53,800 square feet (ft\2\)), separated by stream reaches 
in which mussels are absent or rare (Vaughn 2012, p. 983). Resilient 
Texas hornshell populations must occupy stream reaches sufficient in 
length such that stochastic events that affect individual mussel beds 
do not eliminate the entire population. Repopulation by fish infested 
with Texas hornshell glochidia from other mussel beds within the reach, 
if present and connected, can allow the population to recover from 
these events.
    Abundance: Mussel abundance in a given stream reach is a product of 
the number of mussel beds times the density of mussels within those 
beds. For populations of Texas hornshell to be resilient, there must be 
many mussel beds of sufficient density (~200 individuals per 150 m\2\ 
(1,614 ft\2\); see SSA report for more discussion) such that local 
stochastic events do not necessarily eliminate the bed(s), allowing the 
mussel bed and the overall population in the stream reach to recover 
from any one event. We measure Texas hornshell abundance by the number 
of beds within the population, and the estimated density of Texas 
hornshell within each.
    Reproduction: Resilient Texas hornshell populations must also be 
reproducing and recruiting young individuals into the reproducing 
population. Population size and abundance reflects previous influences 
on the population and habitat, while reproduction and recruitment 
reflect population trends that may be stable, increasing, or 
decreasing. Detection of very young juvenile mussels during routine 
abundance and distribution surveys happens extremely rarely due to 
sampling bias; sampling for this species involves tactile searches, and 
mussels below about 35 millimeters (mm) (1.4

[[Page 52801]]

inches (in)) are very hard to detect. Therefore, reproduction is 
verified by repeatedly capturing small-sized individuals near the low 
end of the detectable range size (about 35 mm (1.4 in)) over time and 
by capturing gravid females during the reproductively active time of 
year (generally, March through August (Smith et al. 2003, p. 335)).
    Substrate: Texas hornshell occur in flow refuges such as crevices, 
undercut riverbanks, travertine shelves, and large boulders. These 
refuges must have seams of clay or other fine sediments within which 
the mussels may anchor, but not so much excess sediment that the 
mussels are smothered. Those areas with clean-swept substrate with 
seams of fine sediments are considered to have suitable substrate, and 
those with copious fine sediment both in crevices and on the stream 
bottom are considered less suitable.
    Flowing Water: Texas hornshell need flowing water for survival. 
They are not found in lakes or in pools without flow, or in areas that 
are regularly dewatered. River reaches with continuous flow are 
considered suitable habitat, while those with little or no flow are 
considered not suitable.
    Water Quality: Freshwater mussels, as a group, are sensitive to 
changes in water quality parameters such as dissolved oxygen, salinity, 
ammonia, and pollutants (i.e., dissolved oxygen above 3 mg/L, salinity 
below 0.9 parts per thousand, and ammonia below 0.7 mg/L (Sparks and 
Strayer 1998, p. 132; Augspurger et al. 2003, p. 2574; Augspurger et 
al. 2007, p. 2025; Carman 2007, p. 6)). Habitats with appropriate 
levels of these parameters are considered suitable, while those 
habitats with levels outside of the appropriate ranges are considered 
less suitable.
    Maintaining representation in the form of genetic or ecological 
diversity is important to maintain the Texas hornshell's capacity to 
adapt to future environmental changes. Texas hornshell populations in 
the Rio Grande and Devils River (and, presumably, the Pecos River, due 
to its proximity to Rio Grande populations) have distinct variation in 
allele frequencies from those in the Black River (Inoue et al. 2015, p. 
1916). We expect additional variation was present in Mexican 
populations. Mussels, like Texas hornshell, need to retain populations 
throughout their range to maintain the overall potential genetic and 
life-history attributes that can buffer the species' response to 
environmental changes over time (Jones et al. 2006, p. 531). The Texas 
hornshell has likely lost genetic diversity as populations have been 
extirpated. As such, maintaining the remaining representation in the 
form of genetic diversity may be important to the capacity of the Texas 
hornshell to adapt to future environmental change.
    Finally, the Texas hornshell needs to have multiple resilient 
populations distributed throughout its range to provide for redundancy, 
the ability of the species to withstand catastrophic events. The more 
populations, and the wider the distribution of those populations, the 
more redundancy the species will exhibit. Redundancy reduces the risk 
that a large portion of the species' range will be negatively affected 
by a catastrophic natural or anthropogenic event at a given point in 
time. Species that are well-distributed across their historical range 
are considered less susceptible to extinction and have higher viability 
than species confined to a small portion of their range (Carroll et al. 
2010, entire; Redford et al. 2011, entire).

Summary of Biological Status and Threats

    The Act directs us to determine whether any species is an 
endangered species or a threatened species because of any factors 
affecting its continued existence. We completed a comprehensive 
assessment of the biological status of the Texas hornshell, and 
prepared a report of the assessment, which provides a thorough account 
of the species' overall viability. In this section, we summarize the 
conclusions of that assessment, which can be accessed at Docket No. 
FWS-R2-ES-2016-0077 on http://www.regulations.gov.

Risk Factors

    We reviewed the potential risk factors (i.e., threats, stressors) 
that could be affecting the Texas hornshell now and in the future. In 
this proposed rule, we will discuss only those factors in detail that 
could meaningfully impact the status of the species. Those risks that 
are not known to have effects on Texas hornshell populations, such as 
collection and disease, are not discussed here. The primary risk 
factors (i.e., threats) affecting the status of the Texas hornshell 
are: (1) Increased fine sediment (Factor A from the Act), (2) water 
quality impairment (Factor A), (3) loss of flowing water (Factor A), 
(4) barriers to fish movement (Factor E), and (5) increased predation 
(Factor C). These factors are all exacerbated by climate change. 
Finally, we reviewed the conservation efforts being undertaken for the 
species.
Increased Fine Sediment
    Texas hornshell require seams of fine sediment under boulders and 
bedrock and in streambanks in order to anchor themselves into place on 
the stream bottom; however, too much fine sediment can fill in these 
crevices and smother any mussels within those spaces. Under natural 
conditions, fine sediments collect on the streambed and in crevices 
during low flow events, and they are washed downstream during high flow 
events (also known as cleansing flows). However, the increased 
frequency of low flow events (from groundwater extraction, instream 
surface flow diversions, and drought), combined with a decrease in 
cleansing flows (from reservoir management and drought), has caused 
sediment to accumulate to some degree at all populations. When water 
velocity decreases, which can occur from reduced streamflow or 
inundation, water loses its ability to carry sediment in suspension; 
sediment falls to the substrate, eventually smothering mussels that 
cannot adapt to soft substrates (Watters 2000, p. 263). Sediment 
accumulation can be exacerbated when there is a simultaneous increase 
in the sources of fine sediments in a watershed. In the range of Texas 
hornshell, these sources include streambank erosion from agricultural 
activities, livestock grazing, and roads, among others.
    Interstitial spaces (small openings between rocks and gravels) in 
the substrate provide essential habitat for juvenile mussels. Juvenile 
freshwater mussels burrow into interstitial substrates, making them 
particularly susceptible to degradation of this habitat feature. When 
clogged with sand or silt, interstitial flow rates and spaces may 
become reduced (Brim Box and Mossa 1999, p. 100), thus reducing 
juvenile habitat availability.
    All populations of Texas hornshell face the risk of fine sediment 
accumulation to varying degrees. Elimination of Texas hornshell from 
mussel beds due to large amounts of sediment deposition has been 
documented on the Black River in two locations in recent years. In the 
future, we expect this may continue to occur sporadically. Fine 
sediments are also accumulating at the Rio Grande--Laredo population. 
Low water levels on the Devils River will likely lead to additional 
sediment accumulation at this population, as well. In the future, we 
expect lower flows to occur more often at all populations and for 
longer periods due to climate change.

[[Page 52802]]

Water Quality Impairment
    Water quality can be impaired through contamination or alteration 
of water chemistry. Chemical contaminants are ubiquitous throughout the 
environment and are a major reason for the current declining status of 
freshwater mussel species nationwide (Augspurger et al. 2007, p. 2025). 
Chemicals enter the environment through both point and nonpoint 
discharges, including spills, industrial sources, municipal effluents, 
and agricultural runoff. These sources contribute organic compounds, 
heavy metals, pesticides, herbicides, and a wide variety of newly 
emerging contaminants to the aquatic environment. Ammonia is of 
particular concern below water treatment plants because freshwater 
mussels have been shown to be particularly sensitive to increased 
ammonia levels (Augspurger et al. 2003, p. 2569). It is likely for this 
reason that Texas hornshell are not found for many miles downstream of 
two wastewater treatment plants that discharge into the Rio Grande: at 
Nuevo Laredo, Mexico, and at Eagle Pass, Texas (Karatayev et al. 2015, 
p. 14).
    An additional type of water quality impairment is alteration of 
water quality parameters such as dissolved oxygen, temperature, and 
salinity levels. Dissolved oxygen levels may be reduced from increased 
nutrients in the water column from runoff or wastewater effluent, and 
juveniles seem to be particularly sensitive to low dissolved oxygen 
(Sparks and Strayer 1998, pp. 132-133). Increased water temperature 
from climate change and from low flows during drought can exacerbate 
low dissolved oxygen levels as well as have its own effects on both 
juvenile and adult mussels. Finally, salinity appears to be 
particularly limiting to Texas hornshell. The aquifer near Malaga, New 
Mexico, contains saline water. As the saline water emerges from the 
ground, it is diluted by surface flow. As surface flow decreases, 
however, the concentration of salinity in the river increases. 
Additionally, aquifers have become increasingly saline due to salinized 
water recharge (Hoagstrom 2009, p. 35). Irrigation return flows 
exacerbate salinity levels as salts build up on irrigated land and then 
are washed into the riverway. The Pecos River from the confluence with 
the Black River to the confluence with Independence Creek has become 
particularly saline in the past few decades, with levels at 7 parts per 
million (ppm) or higher, which is too high for freshwater mussel 
habitation. Additionally, the Black River downstream of the Texas 
hornshell population has had salinity levels in the range of 6 ppm, 
which may be one reason the population has been extirpated from the 
downstream reach.
    Contaminant spills are also a concern. In particular, the Black 
River population is vulnerable to spills from the high volume of truck 
traffic crossing the river at low water access points (Bren School of 
Environmental Management 2014, p. 26). Due to the topography and steep 
slopes of these areas, spilled contaminants and contaminated soils 
could directly enter the surface water of the river and negatively 
impact the species (Boyer 1986, p. 300) and downstream habitat. For the 
smaller populations (Black, Devils, Pecos rivers), a single spill could 
eliminate the entire population.
    A reduction in surface flow from drought, instream diversion, or 
groundwater extraction concentrates contaminant and salinity levels, 
increases water temperatures in streams, and exacerbates effects to 
Texas hornshell.
    Poor water quality affects most Texas hornshell populations 
currently to some degree, and future water quality is expected to 
decrease due to decreasing river flow and increasing temperatures. The 
Pecos River experiences very high salinity levels upstream of the 
existing population, and we expect that the observed high mortality of 
the Pecos River population is due to salinity pulses. Rangewide, as 
water flow is expected to decrease due to climate change, water quality 
will decline.
Loss of Flowing Water
    Texas hornshell populations need flowing water in order to survive. 
Low flow events (including stream drying) and inundation can eliminate 
appropriate habitat for Texas hornshell, and while the species can 
survive these events if they last for a short time, populations that 
experience these events regularly will not persist.
    Inundation has primarily occurred upstream of dams, both large 
(such as Amistad, Falcon, and Red Bluff Dams) and small (low water 
crossings and diversion dams, such as those on the Black River). 
Inundation causes an increase in sediment deposition, eliminating the 
crevices this species inhabits. In large reservoirs, deep water is very 
cold and often devoid of oxygen and necessary nutrients. Cold water 
(less than 11 degrees Celsius ([deg]C) (52 degrees Fahrenheit 
([deg]F))) has been shown to stunt mussel growth (Hanson et al. 1988, 
p. 352). Because glochidial release may be temperature dependent, it is 
likely that relict individuals living in the constantly cold 
hypolimnion (deepest portion of the reservoir) in these reservoirs may 
never reproduce, or reproduce less frequently. Additionally, the 
effects of these reservoirs extend beyond inundation and fragmentation 
of populations; the reservoirs are managed for flood control and water 
delivery, and the resultant downstream releases rarely mimic natural 
flow regimes, tempering the natural fluctuations in flow that flush 
fine sediments from the substrate.
    At the Rio Grande--Laredo population, a low-water weir has been 
proposed for construction (Rio Grande Regional Water Planning Group 
2016, p. 8-8). The dam would be located just downstream of the La Bota 
area, which contains the largest known and most dense Texas hornshell 
bed within the Rio Grande--Laredo population and rangewide. The 
impounded area would extend approximately 14 mi (22.5 km) upstream, 
effectively eliminating habitat for Texas hornshell from 25 percent of 
the currently occupied area and likely leading to extirpation of the 
densest sites within this population.
    Very low water levels are detrimental to Texas hornshell 
populations, as well. Effects of climate change have already begun to 
affect the regions of Texas and New Mexico where the Texas hornshell 
occurs, resulting in higher air temperatures, increased evaporation, 
increased groundwater pumping, and changing precipitation patterns such 
that water levels rangewide have already reached historic lows (Dean 
and Schmidt 2011, p. 336; Bren School of Environmental Management 2014, 
p. 50). The rivers inhabited by Texas hornshell have some resiliency to 
drought because they are spring-fed (Black and Devils Rivers) and very 
large (Rio Grande), but drought in combination with increased 
groundwater pumping and regulated reservoir releases may lead to lower 
river flows of longer duration than have been recorded in the past. 
Streamflow in the Rio Grande downstream of the confluence with the Rio 
Conchos (near the Rio Grande-Lower Canyons population) has been 
declining since the 1980s (Miyazono et al. 2015, p. A-3), and overall 
river discharge for the Rio Grande is projected to continue to decline 
due to increased drought as a result of climate change (Nohara et al. 
2006, p. 1087). The Rio Conchos contributes more than 90 percent of the 
flow of the lower Rio Grande (Dean and Schmidt 2011, p. 4). However, 
during times of drought (such as between 1994 and 2003), Mexico has 
fallen short of its water delivery commitments, and so the contribution 
of the Rio Conchos has fallen to as low as 40 percent (Carter et

[[Page 52803]]

al. 2015, p. 15). The Rio Grande--Lower Canyons population is 
downstream of the confluence with the Rio Conchos and is at risk from 
these reduced deliveries. The Rio Grande--Lower Canyons is very incised 
(in other words, has vertical banks), and the population occurs in 
crevices along the steep banks. Due to the habitat characteristics of 
this population, reductions in discharge in this area may lead to a 
higher proportion of the Texas hornshell population being exposed than 
would be found in other populations experiencing similar flow 
decreases.
    In the Black River, surface water is removed from the river for 
irrigation, including the Carlsbad Irrigation District's Black River 
Canal at the diversion dam. Studies have shown that flows in the river 
are affected by groundwater withdrawals, particularly those from the 
Black River Valley. Groundwater in the Black River watershed is also 
being used for hydraulic fracturing for oil and gas activities. Between 
4.3 acre-feet (187,308 ft\3\ (5,304 m\3\)) and 10.7 acre-feet (466,091 
ft\3\ (13,198 m3)) of water is used for each hydraulic fracturing job 
(Bren School of Environmental Management 2014, p. 91). Overall, mean 
monthly discharge has already declined since the mid-1990s, and mean 
monthly temperatures have increased over the past 100 years (Inoue et 
al. 2014, p. 7). In the Black River, survivorship is positively 
correlated with discharge (Inoue et al. 2014, p. 9); as mean monthly 
discharge decreases, we expect Texas hornshell survivorship to 
decrease, as well. The Black River is expected to lose streamflow in 
the future due to air temperature increases, groundwater extraction, 
and reduced precipitation.
    In the Devils River, future water withdrawals from aquifers that 
support spring flows in the range of the Texas hornshell could result 
in reduction of critical spring flows and river drying. In particular, 
there have been multiple proposals to withdraw water from the nearby 
aquifer and deliver the water to municipalities (e.g., Val Verde Water 
Company 2013, pp. 1-2). To date, however, none have been approved.
    As spring flows decline due to drought or groundwater lowering from 
pumping, habitat for the Texas hornshell is reduced and could 
eventually cease to exist. While Texas hornshell may survive short 
periods of low flow, as low flows persist, mussels face oxygen 
deprivation, increased water temperature, and, ultimately, stranding.
Barriers to Fish Movement
    Two of the Texas hornshell's primary host fish species (river 
carpsucker and red shiner) are known to be common, widespread species. 
We do not expect the distribution of host fish to be a limiting factor 
in Texas hornshell distribution. However, the barriers that prevent 
fish movement upstream and downstream affect the viability of Texas 
hornshell.
    Texas hornshell were likely historically distributed throughout the 
Rio Grande, Pecos River, Devils River, and Black River in Texas and New 
Mexico, as well as throughout the rivers draining to the Gulf of Mexico 
from which the species was known when few natural barriers existed to 
prevent migration (via host species) among suitable habitats. The 
species colonized new areas through movement of infested host fish, and 
newly metamorphosed juveniles would excyst from host fish in new 
locations. Today, the remaining populations are significantly isolated 
from one another such that recolonization of areas previously 
extirpated is extremely unlikely if not impossible due to existing 
contemporary barriers to host fish movement. The primary reason for 
this isolation is reservoir construction and unsuitable water quality. 
The Black River is isolated from the rest of the populations by high 
salinity reaches of the Pecos River, as well as Red Bluff Reservoir, 
and is hundreds of river miles from the nearest extant population. 
Amistad Reservoir separates the three Texas populations from each 
other, isolating the Rio Grande--Lower Canyons, Devils River, and Rio 
Grande--Laredo populations. There is currently no opportunity for 
interaction among any of the five extant U.S. populations.
    The overall distribution of mussels is, in part, a function of the 
dispersal of their host fish. Small populations are more affected by 
this limited immigration potential because they are susceptible to 
genetic drift (random loss of genetic diversity) and inbreeding 
depression. At the species level, populations that are eliminated due 
to stochastic events cannot be recolonized naturally, leading to 
reduced overall redundancy and representation.
Increased Predation
    Predation on freshwater mussels is a natural ecological 
interaction. Raccoons, snapping turtles, and fish are known to prey 
upon Texas hornshell. Under natural conditions, the level of predation 
occurring within Texas hornshell populations is not likely to pose a 
significant risk to any given population. However, during periods of 
low flow, terrestrial predators have increased access to portions of 
the river that are otherwise too deep under normal flow conditions. 
High levels of predation during drought have been observed on the 
Devils River, and muskrat predation has also been reported on the Black 
River. As drought and low flow conditions are predicted to occur more 
often and for longer periods due to the effects of climate change, the 
Black and Devils Rivers are expected to experience additional predation 
pressure into the future. Predation is expected to be less of a concern 
for the Rio Grande populations, as the river is significantly larger 
than the Black and Devils Rivers and Texas hornshell are less likely to 
be found in exposed or very shallow portions of the stream.
Effects of Climate Change
    Climate change in the form of the change in timing and amount of 
precipitation and air temperature increase is occurring, and continued 
greenhouse gas emissions at or above current rates will cause further 
warming (Intergovernmental Panel on Climate Change (IPCC) 2013, pp. 11-
12). Warming in the Southwest is expected to be greatest in the summer 
(IPCC 2013, pp. 11-12), and annual mean precipitation is very likely to 
decrease in the Southwest (Ray et al. 2008, p. 1; IPCC 2013, pp. 11-
12). In Texas, the number of extreme hot days (high temperatures 
exceeding 95 [deg]F (35 [deg]C) are expected to double by around 2050 
(Kinniburgh et al. 2015, p. 83), and Texas is considered one of the 
``hotspots'' of climate change in North America; west Texas is an area 
expected to show greater responsiveness to the effects of climate 
change (Diffenbaugh et al. 2008, p. 3). Even if precipitation and 
groundwater recharge remain at current levels, increased groundwater 
pumping and resultant aquifer shortages due to increased temperatures 
are nearly certain (Loaiciga et al. 2000, p. 193; Mace and Wade 2008, 
pp. 662, 664-665; Taylor et al. 2012, p. 3). Increased water 
temperature can cause stress to individuals, decrease dissolved oxygen 
levels, and increase toxicity of contaminants. Effects of climate 
change, such as air temperature increases and an increase in drought 
frequency and intensity, have been shown to be occurring throughout the 
range of Texas hornshell (Kinniburgh et al. 2015, p. 88), and these 
effects are expected to exacerbate several of the stressors discussed 
above, such as water temperature and flow loss (Wuebbles et

[[Page 52804]]

al. 2013, p. 16). As we projected the future condition of the Texas 
hornshell and which stressors are likely to occur, we considered 
climate change to be an exacerbating factor in the increase of fine 
sediments, changes in water quality, and loss of flowing water.
    Due to the effects of ongoing climate change, we expect the 
frequency and duration of cleansing flows to decrease, leading to the 
increase in fine sediments and reduced water levels at all populations. 
More extreme climate change projections lead to further increases in 
fine sediment within the populations. Similarly, as lower water levels 
concentrate contaminants and cause unsuitable temperature and dissolved 
oxygen levels, we expect water quality to decline to some degree in the 
future.

Conservation Actions and Regulatory Mechanisms

    About 7 percent of known occupied habitat for the Texas hornshell 
is in New Mexico, and the Service is collaborating with water users, 
oil and gas developers, landowners, and other partners to develop 
candidate conservation agreements (CCAs) for the species on State, 
Federal, and private lands. These agreements are currently under 
development, and the potential purpose is to provide voluntary 
conservation that would reduce threats to the species while improving 
physical habitat and water quality. The key conservation measures in 
the agreements will be designed to limit oil and gas development to 
areas outside of the Black and Delaware River floodplains, minimize 
erosion, and maintain minimum water flows in the rivers. Along with 
these measures, the partners to the agreement are evaluating 
alternatives to the multiple low water crossings on the Black River. 
Partners are considering alternate crossing locations, which could 
include bridges designed to allow host fishes to pass through in 
addition to decreasing potential contamination events. Because these 
agreements have not been completed, we are not considering the 
conservation actions in our present evaluation of the status of Texas 
hornshell.
    The New Mexico Department of Game and Fish has begun Texas 
hornshell reintroduction efforts into the Delaware River, which is 
within the historical range of the species. Adults and infested host 
fish were released in suitable habitat in the Delaware River in 2013 
and 2015. Many of the released adults have been subsequently located, 
and success of the reintroduction will be determined in the coming 
years. We expect the reintroduction effort to continue over the next 
several years, but we are not considering the action to have been 
successful to date.
    In Texas, The Nature Conservancy and Texas Parks and Wildlife 
Department manage lands under their purview in the Devils River 
watershed for native communities, including Texas hornshell. The large 
amount (over 200,000 acres) of land in conservation management in the 
Devils River watershed reduces the risks to Texas hornshell from 
sediment inputs and contaminants.
    In the Rio Grande, we are not aware of any management actions for 
Texas hornshell. The Texas Comptroller of Public Accounts has 
established an Endangered Species Task Force and has funded much of the 
recent research in Texas on Texas hornshell, which has led to greater 
understanding of the species' distribution in the State.

Current Condition

    Overall, there are five known remaining populations of Texas 
hornshell, comprising approximately 15 percent of the species' 
historical range in the United States (see Map 1, above). Historically, 
most Texas hornshell populations were likely connected by fish 
migration throughout the Rio Grande, upstream through the Pecos River, 
and throughout the tributaries, but due to impoundments and river 
reaches with unsuitable water quality (for example, high salinity) they 
are currently isolated from one another, and repopulation of extirpated 
locations is unlikely to occur without human assistance. Here we 
discuss the current condition of each known population, taking into 
account the risks to those populations that are currently occurring, as 
well as management actions that are currently occurring to address 
those risks. We consider low levels of climate change to be currently 
occurring, resulting in reduced timing and amount of streamflow, 
increased stream temperatures, and increased accumulation of fine 
sediments.
    Black River: The Black River population is quite dense and 
recruitment appears to be high, but the short size (8.7 mi (14.0 km)) 
of the occupied reach limits this population's resiliency. Accumulation 
of fine sediment in the substrate has already occurred due to increased 
sediment input into the river from road crossings, culverts, and cattle 
grazing, combined with a decreased frequency of cleansing river flows. 
The current level of climate change will continue to reduce flow in the 
river from groundwater extraction and drought, resulting in fewer 
cleansing flows and increased fine sediments. The distribution of Texas 
hornshell in the Black River will remain small, and the risk of a 
contaminant spill will remain high, resulting in a high likelihood that 
water quality will become unsuitable and reduce abundance of Texas 
hornshell significantly. Therefore, taking into account the current 
threats to the population and its distribution within the river, the 
Texas hornshell population in the Black River has low resiliency.
    Pecos River: The Pecos River population is extremely small and 
exhibits no evidence of reproduction. The few number of live 
individuals among the very high number of dead shells indicates a 
population in severe decline; this is likely due to high salinity 
levels in the river upstream of the population. There is a high 
likelihood this population will be extirpated in the near future due to 
water quality alone. Therefore, the Pecos River population of Texas 
hornshell has very low resiliency.
    Devils River: The Devils River population has low abundance and has 
exhibited some evidence of reproduction. The current level of climate 
change will continue to reduce flow in the Devils River due to 
groundwater extraction and drought. The low flows this population 
experiences during dry times will continue to become more frequent and 
prolonged. Because Texas hornshell in the Devils River occur at the 
heads of riffles, they are vulnerable to complete flow loss when water 
levels drop. The reduction in cleansing flows will also result in the 
accumulation of fine sediments, reducing substrate quality. Low flows 
will also affect water quality parameters such as temperature and 
dissolved oxygen, causing them to become unsuitable for Texas 
hornshell. Additionally, the species is already vulnerable to predation 
from terrestrial predators during times of low flow; predation will 
occur more frequently as periods of low flow become more common. 
Overall, because the population is currently small and would be 
unlikely to grow, the Devils River population has low resiliency.
    Rio Grande--Lower Canyons: The Lower Canyons population has 
relatively high abundance and evidence of recruitment. Drought and 
groundwater extraction resulting from currently observed levels of 
climate change will continue to lower water levels in the Rio Grande--
Lower Canyons population of Texas hornshell. We expect that Mexico's 
management of the Rio Conchos will continue to be an

[[Page 52805]]

unreliable source of water. This section of the Rio Grande is 
relatively deep and incised, and the population of Texas hornshell 
primarily occurs in crevices along the banks. Water flow reductions 
would expose a high proportion of the existing population; therefore, 
this reduction in flow will likely have a larger effect on the 
population size than in other populations, although at a small to 
moderate decrease in water flow we still expect abundance to be 
maintained at moderate levels. Overall, the Rio Grande--Lower Canyons 
population exhibits moderate resiliency.
    Rio Grande--Laredo: Similar to the Lower Canyons population, the 
Laredo population has numerous mussel beds with high Texas hornshell 
abundance and evidence of reproduction. However, drought and upstream 
water management will continue to reduce flows in the Rio Grande. Water 
quality will continue to decrease due to lower flows, and fine 
sediments will accumulate. Declining water flow will cause fine 
sediments to accumulate and water quality to decline, leading to a 
decline in population abundance. Overall, the Rio Grande--Laredo has 
moderate resiliency.
    Mexico: We have low confidence in the species' current condition 
throughout most of the Mexican range. One or more of these populations 
may still be extant, or they may all be extirpated. We have no recent 
data on the species' occurrence in Mexico; the last live recordings are 
from the mid-1980s. Because of this uncertainty, we did not rely on the 
Texas hornshell's distribution in Mexico when evaluating the viability 
of the species.

Future Condition

    As part of the SSA, we also developed multiple future condition 
scenarios to capture the range of uncertainties regarding future 
threats and the projected responses by the Texas hornshell. Our 
scenarios included a status quo scenario, which incorporated the 
current risk factors continuing on the same trajectory that they are on 
now. We also evaluated four additional future scenarios that 
incorporated varying levels of increasing risk factors with elevated 
negative effects on hornshell populations. However, because we 
determined that the current condition of the Texas hornshell and the 
associated status quo projections were consistent with an endangered 
species (see Determination, below), we are not presenting the results 
of the other future scenarios in this proposed rule. The additional 
future scenarios project conditions that are worse for the Texas 
hornshell. Since the status quo scenario was determined to be 
endangered, other projected scenarios would also be endangered, as they 
forecast conditions that are more at risk of extinction than the status 
quo. Please refer to the SSA report (Service 2016) for the full 
analysis of future scenarios.

Determination

    Section 4 of the Act, and its implementing regulations at 50 CFR 
part 424, set forth the procedures for adding species to the Federal 
Lists of Endangered and Threatened Wildlife and Plants. Under section 
4(b)(1)(a), the Secretary is to make endangered or threatened 
determinations required by subsection 4(a)(1) solely on the basis of 
the best scientific and commercial data available to her after 
conducting a review of the status of the species and after taking into 
account conservation efforts by States or foreign nations. The 
standards for determining whether a species is endangered or threatened 
are provided in section 3 of the Act. An endangered species is any 
species that is ``in danger of extinction throughout all or a 
significant portion of its range.'' A threatened species is any species 
that is ``likely to become an endangered species within the foreseeable 
future throughout all or a significant portion of its range.'' Per 
section 4(a)(1) of the Act, in reviewing the status of the species to 
determine if it meets the definition of endangered or of threatened, we 
determine whether any species is an endangered species or a threatened 
species because of any of the following five factors: (A) The present 
or threatened destruction, modification, or curtailment of its habitat 
or range; (B) overutilization for commercial, recreational, scientific, 
or educational purposes; (C) disease or predation; (D) the inadequacy 
of existing regulatory mechanisms; and (E) other natural or manmade 
factors affecting its continued existence. Listing actions may be 
warranted based on any of the above threat factors, singly or in 
combination.
    The fundamental question before the Service is whether the species 
warrants protection as an endangered or threatened species under the 
Act. To make this determination, we evaluated extinction risk, 
described in terms of the current condition of populations and their 
distribution (taking into account the risk factors (i.e., threats, 
stressors) and their effects on those populations). For any species, as 
population conditions decline and distribution shrinks, the species' 
overall viability declines and extinction risk increases.
    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Texas hornshell. Our analysis of the past, current, and future 
influences on what the Texas hornshell needs for long-term viability 
revealed that there are five influences that may pose a meaningful risk 
to the viability of the species. These are primarily related to habitat 
changes (Factor A from the Act): The accumulation of fine sediments, 
the loss of flowing water, and impairment of water quality, all of 
which are exacerbated by the effects of climate change. Predation 
(Factor C) is also affecting those populations already experiencing low 
stream flow, and barriers to fish movement (Factor E) prevent 
recolonization after stochastic events.
    The Texas hornshell has declined significantly in overall 
distribution and abundance, with the species currently occupying 
approximately 15 percent of its historical range in the United States. 
Between one-half and two-thirds of the Texas hornshell's historical 
range occurred in Mexico; we have very low confidence in the species' 
current condition throughout most of the Mexican range. The resulting 
remnant populations occupy shorter reaches compared to presumed 
historical populations, and they are all isolated from one another.
    The primary historical reason for this reduction in range was 
reservoir construction and unsuitable water quality. Large reservoirs 
have been constructed on the Rio Grande and Pecos River, and much of 
the Pecos River upstream of the confluence with Independence Creek now 
has salinity levels too high for mussel habitation (Hoagstrom 2009, p. 
28). The effects of these reservoirs extend beyond fragmentation of 
populations; the resultant downstream water releases do not mimic 
natural flow regimes, and the change in timing and frequency of 
cleansing flows results in increases in fine sediments, increases in 
predation, and decreases in water quality. Add to this the exacerbating 
effects of climate change--increased temperature and decreased stream 
flow--and the remaining Texas hornshell populations face moderate to 
high levels of risk of extirpation currently. For the populations 
occupying the smaller reaches (such as the Black River, Devils River, 
and Pecos River populations), a single stochastic event such as 
contaminant spill or drought could eliminate an entire population of 
Texas hornshell. These effects are heightened at the species level 
because the isolation of the populations prohibits natural 
recolonization from host fish carrying Texas hornshell glochidia, which 
likely

[[Page 52806]]

happened in the past and allowed for the species to ebb and flow from 
suitable areas.
    Populations in both large and small reaches face risks from natural 
and anthropogenic sources. Climate change has already begun to affect 
the regions of Texas and New Mexico where Texas hornshell occurs, 
resulting in higher air temperatures, increased evaporation, increased 
groundwater pumping, and changing precipitation patterns such that 
water levels rangewide have already reached historic lows. These low 
water levels put the populations at risk of habitat loss from increased 
fine sediments, poor water quality, and increased predation risk.
    These risks, alone or in combination, are expected to result in the 
extirpation of additional populations, further reducing the overall 
redundancy and representation of the species. Historically, the 
species, with a large range of interconnected populations, would have 
been resilient to stochastic events such as drought and sedimentation 
because even if some populations were extirpated by such events, they 
could be recolonized over time by dispersal from nearby surviving 
populations. This connectivity would have made for a highly resilient 
species overall. However, under current conditions, connectivity is 
prevented due to large reservoirs and unsuitably high salinity levels 
between populations. As a consequence of these current conditions, the 
viability of the Texas hornshell now primarily depends on maintaining 
the remaining isolated populations.
    Of the five remaining isolated populations, three are small in 
abundance and occupied stream length and have low to no resiliency. The 
remaining two are larger, with increased abundance and occupied stream 
length; however, flow reduction, water quality decline, and habitat 
loss from sedimentation reduce the abundance and distribution of those 
populations. We have no information on population status in Mexico. 
Therefore, the Texas hornshell has no populations that are currently 
considered highly resilient. The high risk of extirpation of these 
populations leads to low levels of redundancy (few populations will 
persist to withstand catastrophic events) and representation (little to 
no ecological or genetic diversity will persist to respond to changing 
environmental conditions). Overall, these low levels of resiliency, 
redundancy, and representation result in the Texas hornshell having low 
viability, and the species currently faces a high risk of extinction.
    The Act defines an endangered species as any species that is ``in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as any species ``that is likely to 
become endangered throughout all or a significant portion of its range 
within the foreseeable future.'' We find that the Texas hornshell is 
presently in danger of extinction throughout its entire range based on 
the severity and immediacy of threats currently impacting the species. 
The overall range has been significantly reduced, and the remaining 
habitat and populations are threatened by a multitude of factors acting 
in combination to reduce the overall viability of the species. The risk 
of extinction is high because the remaining populations have a high 
risk of extirpation, are isolated, and have limited potential for 
recolonization. Therefore, on the basis of the best available 
scientific and commercial information, we propose listing the Texas 
hornshell as endangered in accordance with sections 3(6) and 4(a)(1) of 
the Act. We find that a threatened species status is not appropriate 
for the Texas hornshell because of the currently contracted range (loss 
of 85 percent of its historic range in the United States, and likely 
more in Mexico), because the threats are occurring across the entire 
range of the species, and because the threats are ongoing currently and 
are expected to continue or worsen into the future. Because the species 
is already in danger of extinction throughout its range, a threatened 
status is not appropriate.
    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. Because we have determined that the 
Texas hornshell is endangered throughout all of its range, no portion 
of its range can be ``significant'' for purposes of the definitions of 
``endangered species'' and ``threatened species.'' See the Final Policy 
on Interpretation of the Phrase ``Significant Portion of Its Range'' in 
the Endangered Species Act's Definitions of ``Endangered Species'' and 
``Threatened Species'' (79 FR 37578; July 1, 2014).

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened species under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies; private 
organizations; and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies and 
the prohibitions against certain activities are discussed, in part, 
below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Subsection 4(f) of the Act calls for the Service to develop 
and implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed and preparation of a draft and final 
recovery plan. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan also identifies 
recovery criteria for review of when a species may be ready for 
downlisting or delisting, and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (composed of species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) are often established to develop recovery plans. When 
completed, the recovery outline, draft recovery plan, and the final 
recovery plan will be available on our Web site (http://www.fws.gov/endangered), or from our Texas Coastal Ecological Services Field Office 
(see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include

[[Page 52807]]

habitat restoration (e.g., restoration of native vegetation), research, 
captive propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their ranges may occur primarily or solely on 
non-Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands. 
If this species is listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the States of Texas and New Mexico 
would be eligible for Federal funds to implement management actions 
that promote the protection or recovery of the Texas hornshell. 
Information on our grant programs that are available to aid species 
recovery can be found at: http://www.fws.gov/grants.
    Although the Texas hornshell is only proposed for listing under the 
Act at this time, please let us know if you are interested in 
participating in recovery efforts for this species. Additionally, we 
invite you to submit any new information on this species whenever it 
becomes available and any information you may have for recovery 
planning purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as an 
endangered or threatened species and with respect to its critical 
habitat, if any is designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any action that is likely to jeopardize the 
continued existence of a species proposed for listing or result in 
destruction or adverse modification of proposed critical habitat. If a 
species is listed subsequently, section 7(a)(2) of the Act requires 
Federal agencies to ensure that activities they authorize, fund, or 
carry out are not likely to jeopardize the continued existence of the 
species or destroy or adversely modify its critical habitat. If a 
Federal action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into consultation with the 
Service.
    Federal agency actions within the species' habitat that may require 
conference or consultation or both as described in the preceding 
paragraph include management and any other landscape-altering 
activities on Federal lands administered by the Bureau of Land 
Management, Bureau of Reclamation, and National Park Service; issuance 
of section 404 Clean Water Act (33 U.S.C. 1251 et seq.) permits by the 
U.S. Army Corps of Engineers; and construction and maintenance of roads 
or highways by the Federal Highway Administration.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to endangered wildlife. 
The prohibitions of section 9(a)(1) of the Act, codified at 50 CFR 
17.21, make it illegal for any person subject to the jurisdiction of 
the United States to take (which includes harass, harm, pursue, hunt, 
shoot, wound, kill, trap, capture, or collect; or to attempt any of 
these) endangered wildlife within the United States or on the high 
seas. In addition, it is unlawful to import; export; deliver, receive, 
carry, transport, or ship in interstate or foreign commerce in the 
course of commercial activity; or sell or offer for sale in interstate 
or foreign commerce any listed species. It is also illegal to possess, 
sell, deliver, carry, transport, or ship any such wildlife that has 
been taken illegally. Certain exceptions apply to employees of the 
Service, the National Marine Fisheries Service, other Federal land 
management agencies, and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered wildlife under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.22. With regard to 
endangered wildlife, a permit may be issued for the following purposes: 
For scientific purposes, to enhance the propagation or survival of the 
species, and for incidental take in connection with otherwise lawful 
activities. There are also certain statutory exemptions from the 
prohibitions, which are found in sections 9 and 10 of the Act.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a proposed 
listing on proposed and ongoing activities within the range of the 
species proposed for listing. Based on the best available information, 
if we list this species, the following actions are unlikely to result 
in a violation of section 9, if these activities are carried out in 
accordance with existing regulations and permit requirements; this list 
is not comprehensive:
    (1) Normal agricultural and silvicultural practices, including 
herbicide and pesticide use, which are carried out in accordance with 
any existing regulations, permit and label requirements, and best 
management practices; and
    (2) Normal residential landscape activities.
    Based on the best available information, if we list this species, 
the following activities may potentially result in a violation of 
section 9 of the Act; this list is not comprehensive:
    (1) Unauthorized handling or collecting of the species;
    (2) Modification of the channel or water flow of any stream in 
which the Texas hornshell is known to occur;
    (3) Livestock grazing that results in direct or indirect 
destruction of stream habitat; and
    (4) Discharge of chemicals or fill material into any waters in 
which the Texas hornshell is known to occur.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Texas 
Coastal Ecological Services Field Office (see FOR FURTHER INFORMATION 
CONTACT).

Critical Habitat for the Texas Hornshell

Background

    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features:
    (a) Essential to the conservation of the species, and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement,

[[Page 52808]]

habitat acquisition and maintenance, propagation, live trapping, and 
transplantation, and, in the extraordinary case where population 
pressures within a given ecosystem cannot be otherwise relieved, may 
include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the requirement that Federal agencies ensure, in consultation 
with the Service, that any action they authorize, fund, or carry out is 
not likely to result in the destruction or adverse modification of 
critical habitat. The designation of critical habitat does not affect 
land ownership or establish a refuge, wilderness, reserve, preserve, or 
other conservation area. Such designation does not allow the government 
or public to access private lands. Such designation does not require 
implementation of restoration, recovery, or enhancement measures by 
non-Federal landowners. Where a landowner requests Federal agency 
funding or authorization for an action that may affect a listed species 
or critical habitat, the consultation requirements of section 7(a)(2) 
of the Act would apply, but even in the event of a destruction or 
adverse modification finding, the obligation of the Federal action 
agency and the landowner is not to restore or recover the species, but 
to implement reasonable and prudent alternatives to avoid destruction 
or adverse modification of critical habitat.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines, provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary designate critical habitat at 
the time the species is determined to be endangered or threatened. Our 
regulations (50 CFR 424.12(a)(1)) state that the designation of 
critical habitat is not prudent when one or both of the following 
situations exist: (1) The species is threatened by taking or other 
human activity, and identification of critical habitat can be expected 
to increase the degree of threat to the species, or (2) such 
designation of critical habitat would not be beneficial to the species.
    There is currently no imminent threat of take attributed to 
collection or vandalism under Factor B for the Texas hornshell, and 
identification and mapping of critical habitat is not likely to 
increase any such threat. In the absence of finding that the 
designation of critical habitat would increase threats to a species, if 
there are any benefits to a critical habitat designation, then a 
prudent finding is warranted. The potential benefits of designation 
include: (1) Triggering consultation under section 7 of the Act in new 
areas for actions in which there may be a Federal nexus where it would 
not otherwise occur because, for example, it is or has become 
unoccupied or the occupancy is in question; (2) focusing conservation 
activities on the most essential features and areas; (3) providing 
educational benefits to State or county governments or private 
entities; and (4) preventing people from causing inadvertent harm to 
the species. Therefore, because we have determined that the designation 
of critical habitat will not likely increase the degree of threat to 
these species and may provide some measure of benefit, we find that 
designation of critical habitat is prudent for the Texas hornshell.

Critical Habitat Determinability

    Having determined that designation is prudent, under section 
4(a)(3) of the Act we must find whether critical habitat for the 
species is determinable. Our regulations at 50 CFR 424.12(a)(2) state 
that critical habitat is not determinable when one or both of the 
following situations exist: (1) Information sufficient to perform 
required analyses of the impacts of the designation is lacking, or (2) 
the biological needs of the species are not sufficiently well known to 
permit identification of an area as critical habitat.
    As discussed above, we have reviewed the available information 
pertaining to the biological needs of this species and habitat 
characteristics where this species is located. Because the biological 
needs are not sufficiently well known to permit identification of 
critical habitat, we are seeking additional information regarding 
updated occurrence records for the Texas hornshell, future climate 
change effects on the species' habitat, and other analyses. Therefore, 
we conclude that the designation of critical habitat is not 
determinable for the Texas hornshell at this time. We will make a 
determination on critical habitat no later than 1 year following any 
final listing determination.

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the numbers of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with listing a species as an endangered or 
threatened species under the Endangered Species Act. We published a 
notice outlining our reasons for this determination in the Federal 
Register on October 25, 1983 (48 FR 49244).

References Cited

    A complete list of references cited is available in Appendix A of 
the SSA Report (U.S. Fish and Wildlife Service. 2016. Species status 
assessment report for the Texas hornshell (Popenaias popeii), Version 
1.0. Albuquerque, NM), available online at http://www.regulations.gov, 
under Docket Number FWS-R2-ES-2016-0077.

[[Page 52809]]

Authors

    The primary authors of this proposed rule are the staff members of 
the Texas Coastal Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless 
otherwise noted.

0
2. Amend Sec.  17.11(h) by adding an entry for ``Hornshell, Texas'' to 
the List of Endangered and Threatened Wildlife in alphabetical order 
under Clams:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

----------------------------------------------------------------------------------------------------------------
                                                                                              Listing citations
           Common name                Scientific name        Where listed         Status        and applicable
                                                                                                    rules
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
              Clams
 
                                                  * * * * * * *
Hornshell, Texas.................  Popenaias popeii....  Wherever found.....  E              [Federal Register
                                                                                              citation when
                                                                                              published as a
                                                                                              final rule.]
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------


    Dated: July 21, 2016.
 Stephen Guertin,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2016-18816 Filed 8-9-16; 8:45 am]
 BILLING CODE P



                                               52796               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                                 2. To assist commenters in reviewing                  enter FWS–R2–ES–2016–0077, which is                     The basis for our action. Under the
                                               this revised proposal, the Board will                   the docket number for this rulemaking.                Act, we can determine that a species is
                                               make its workpapers available to                        Then, in the Search panel on the left                 an endangered or threatened species
                                               commenters subject to the customary                     side of the screen, under the Document                based on any of five factors, acting alone
                                               Confidentiality Agreement.                              Type heading, click on the Proposed                   or in combination: (A) The present or
                                                 3. Comments are due by October 11,                    Rules link to locate this document. You               threatened destruction, modification, or
                                               2016; replies are due by November 7,                    may submit a comment by clicking on                   curtailment of its habitat or range; (B)
                                               2016.                                                   ‘‘Comment Now!’’                                      overutilization for commercial,
                                                 4. A copy of this decision will be                       (2) By hard copy: Submit by U.S. mail              recreational, scientific, or educational
                                               served upon the Chief Counsel for                       or hand-delivery to: Public Comments                  purposes; (C) disease or predation; (D)
                                               Advocacy, Office of Advocacy, U.S.                      Processing, Attn: FWS–R2–ES–2016–                     the inadequacy of existing regulatory
                                               Small Business Administration.                          0077, U.S. Fish and Wildlife Service,                 mechanisms; or (E) other natural or
                                                 5. This decision is effective on its                  MS: BPHC, 5275 Leesburg Pike, Falls                   manmade factors affecting its continued
                                               service date.                                           Church, VA 22041–3803.                                existence. We have determined that the
                                                 Decided: August 2, 2016.                                 We request that you send comments                  Texas hornshell is in danger of
                                                 By the Board, Chairman Elliott, Vice                  only by the methods described above.                  extinction due to habitat loss from loss
                                               Chairman Miller, and Commissioner                       We will post all comments on http://                  of water flow, decreased water quality,
                                               Begeman.                                                www.regulations.gov. This generally                   and increased accumulation of fine
                                               Tia Delano,                                             means that we will post any personal                  sediments (Factor A) and predation
                                               Clearance Clerk.                                        information you provide us (see Public                (Factor C).
                                                                                                       Comments, below, for more                               We will seek peer review. We will seek
                                               [FR Doc. 2016–18806 Filed 8–9–16; 8:45 am]
                                                                                                       information).                                         comments from independent specialists
                                               BILLING CODE 4915–01–P
                                                                                                                                                             to ensure that our determination is
                                                                                                       FOR FURTHER INFORMATION CONTACT:                      based on scientifically sound data,
                                                                                                       Chuck Ardizzone, U.S. Fish and                        assumptions, and analyses. We will
                                               DEPARTMENT OF THE INTERIOR                              Wildlife Service, Texas Coastal                       invite these peer reviewers to comment
                                                                                                       Ecological Services Field Office, 17629               on our listing proposal. Because we will
                                               Fish and Wildlife Service                               El Camino Real #211, Houston, TX                      consider all comments and information
                                                                                                       77058; by telephone 281–286–8282; or                  we receive during the comment period,
                                               50 CFR Part 17                                          by facsimile 281–488–5882. Persons                    our final determination may differ from
                                               [Docket No. FWS–R2–ES–2016–0077;                        who use a telecommunications device                   this proposal.
                                               4500030113]                                             for the deaf (TDD) may call the Federal                 We prepared a species status
                                                                                                       Information Relay Service (FIRS) at                   assessment report (SSA report) for the
                                               RIN 1018–BB34                                           800–877–8339.                                         Texas hornshell. The SSA report
                                               Endangered and Threatened Wildlife                      SUPPLEMENTARY INFORMATION:                            documents the results of the
                                               and Plants; Endangered Species                                                                                comprehensive biological status review
                                                                                                       Executive Summary                                     for the Texas hornshell and provides an
                                               Status for Texas Hornshell
                                                                                                          Why we need to publish a rule. Under               account of the species’ overall viability
                                               AGENCY:    Fish and Wildlife Service,                   the Act, if a species is determined to be             through forecasting of the species’
                                               Interior.                                               an endangered or threatened species                   condition in the future (Service 2016,
                                               ACTION:  Proposed rule.                                 throughout all or a significant portion of            entire). We received feedback from four
                                                                                                       its range, we are required to promptly                scientists with expertise in freshwater
                                               SUMMARY:    We, the U.S. Fish and                       publish a proposal in the Federal                     mussel biology, ecology, and genetics as
                                               Wildlife Service (Service), propose to                  Register and make a determination on                  peer review of the SSA report. The
                                               list the Texas hornshell (Popenaias                     our proposal within 1 year. Critical                  reviewers were generally supportive of
                                               popeii), a freshwater mussel species                    habitat shall be designated, to the                   our approach and made suggestions and
                                               from New Mexico and Texas, as an                        maximum extent prudent and                            comments that strengthened our
                                               endangered species under the                            determinable, for any species                         analysis. The SSA report and other
                                               Endangered Species Act (Act). If we                     determined to be an endangered or                     materials relating to this proposal can be
                                               finalize this rulemaking as proposed, it                threatened species under the Act.                     found at http://www.regulations.gov
                                               would extend the Act’s protections to                   Listing a species as an endangered or                 under Docket No. FWS–R2–ES–2016–
                                               this species.                                           threatened species and designations and               0077.
                                               DATES: We will accept comments                          revisions of critical habitat can only be             Information Requested
                                               received or postmarked on or before                     completed by issuing a rule.
                                               October 11, 2016. Comments submitted                       This rulemaking proposes the listing               Public Comments
                                               electronically using the Federal                        of the Texas hornshell (Popenaias                       We intend that any final action
                                               eRulemaking Portal (see ADDRESSES,                      popeii) as an endangered species. The                 resulting from this proposed rule will be
                                               below) must be received by 11:59 p.m.                   Texas hornshell is a candidate species                based on the best scientific and
                                               Eastern Time on the closing date. We                    for which we have on file sufficient                  commercial data available and be as
                                               must receive requests for public                        information on biological vulnerability               accurate and as effective as possible.
                                               hearings, in writing, at the address                    and threats to support preparation of a               Therefore, we request comments or
Lhorne on DSK30JT082PROD with PROPOSALS




                                               shown in FOR FURTHER INFORMATION                        listing proposal, but for which                       information from other concerned
                                               CONTACT by September 26, 2016.                          development of a listing regulation has               governmental agencies, Native
                                               ADDRESSES: You may submit comments                      been precluded by other higher priority               American tribes, the scientific
                                               by one of the following methods:                        listing activities. This proposed rule                community, industry, or any other
                                                  (1) Electronically: Go to the Federal                reassesses all available information                  interested parties concerning this
                                               eRulemaking Portal: http://                             regarding the status of and threats to the            proposed rule. We particularly seek
                                               www.regulations.gov. In the Search box,                 Texas hornshell.                                      comments concerning:


                                          VerDate Sep<11>2014   13:58 Aug 09, 2016   Jkt 238001   PO 00000   Frm 00017   Fmt 4702   Sfmt 4702   E:\FR\FM\10AUP1.SGM   10AUP1


                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                           52797

                                                  (1) The Texas hornshell’s biology,                   in making a determination, as section                 Previous Federal Actions
                                               range, and population trends, including:                4(b)(1)(A) of the Act directs that                       We identified the Texas hornshell as
                                                  (a) Biological or ecological                         determinations as to whether any                      a Category 2 candidate species in our
                                               requirements of the species, including                  species is an endangered or threatened                January 6, 1989, Review of Vertebrate
                                               habitat requirements for feeding and                    species must be made ‘‘solely on the                  Wildlife (54 FR 554). Category 2
                                               spawning;                                               basis of the best scientific and                      candidates were defined as species for
                                                  (b) Genetics and taxonomy;                           commercial data available.’’                          which we had information that
                                                  (c) Historical and current range,                      You may submit your comments and                    proposed listing was possibly
                                               including distribution patterns;                        materials concerning this proposed rule
                                                  (d) Historical and current population                                                                      appropriate, but conclusive data on
                                                                                                       by one of the methods listed in                       biological vulnerability and threats were
                                               levels, and current and projected trends;               ADDRESSES. We request that you send
                                               and                                                                                                           not available to support a proposed rule
                                                                                                       comments only by the methods                          at the time. The species remained a
                                                  (e) Past and ongoing conservation                    described in ADDRESSES.
                                               measures for the species, its habitat, or                                                                     Category 2 candidate in subsequent
                                                                                                         If you submit information via http://               annual candidate notices of review
                                               both.                                                   www.regulations.gov, your entire
                                                  (2) Factors that may affect the                                                                            (CNOR) (56 FR 58804, November 21,
                                                                                                       submission—including any personal                     1991, and 59 FR 58982, November 15,
                                               continued existence of the species,
                                                                                                       identifying information—will be posted                1994). In the February 28, 1996, CNOR
                                               which may include habitat modification
                                                                                                       on the Web site. If your submission is                (61 FR 7596), we discontinued the
                                               or destruction, overutilization, disease,
                                                                                                       made via a hardcopy that includes                     designation of Category 2 species as
                                               predation, the inadequacy of existing
                                                                                                       personal identifying information, you                 candidates; therefore, the Texas
                                               regulatory mechanisms, or other natural
                                                                                                       may request at the top of your document               hornshell was no longer a candidate
                                               or manmade factors.
                                                                                                       that we withhold this information from                species.
                                                  (3) Biological, commercial trade, or
                                                                                                       public review. However, we cannot                        Subsequently, in 2001, the Texas
                                               other relevant data concerning any
                                                                                                       guarantee that we will be able to do so.              hornshell was added to the candidate
                                               threats (or lack thereof) to this species
                                                                                                       We will post all hardcopy submissions                 list (66 FR 54808, October 30, 2001).
                                               and existing regulations that may be
                                                                                                       on http://www.regulations.gov.                        Candidates are those fish, wildlife, and
                                               addressing those threats.
                                                  (4) Additional information concerning                  Comments and materials we receive,                  plants for which we have on file
                                               the historical and current status, range,               as well as supporting documentation we                sufficient information on biological
                                               distribution, and population size of this               used in preparing this proposed rule,                 vulnerability and threats to support
                                               species, including the locations of any                 will be available for public inspection               preparation of a listing proposal, but for
                                               additional populations of this species,                 on http://www.regulations.gov, or by                  which development of a listing rule is
                                               particularly in Mexico.                                 appointment, during normal business                   precluded by other higher priority
                                                  (5) Information related to climate                   hours, at the U.S. Fish and Wildlife                  listing activities. The Texas hornshell
                                               change within the range of the Texas                    Service, Texas Coastal Ecological                     was included in all of our subsequent
                                               hornshell and how it may affect the                     Services Field Office (see FOR FURTHER                annual CNORs (67 FR 40657, June 13,
                                               species’ habitat.                                       INFORMATION CONTACT).                                 2002; 69 FR 24876, May 4, 2004; 70 FR
                                                  (6) The reasons why areas should or                  Public Hearing                                        24870, May 11, 2005; 71 FR 53756,
                                               should not be designated as critical                                                                          September 12, 2006; 72 FR 69034,
                                               habitat as provided by section 4 of the                   Section 4(b)(5) of the Act provides for             December 6, 2007; 73 FR 75176,
                                               Act (16 U.S.C. 1531 et seq.)                            one or more public hearings on this                   December 10, 2008; 74 FR 57804,
                                                  (7) Specific information on:                         proposal, if requested. Requests must be              November 9, 2009; 75 FR 69222,
                                                  (a) The amount and distribution of                   received within 45 days after the date of             November 10, 2010; 76 FR 66370,
                                               habitat for the Texas hornshell;                        publication of this proposed rule in the              October 26, 2011; 77 FR 69994,
                                                  (b) What areas, that are currently                   Federal Register (see DATES, above).                  November 21, 2012; 78 FR 70104;
                                               occupied and that contain the physical                  Such requests must be sent to the                     November 22, 2013; 79 FR 72450,
                                               and biological features essential to the                address shown in FOR FURTHER                          December 5, 2014; and 80 FR 80584,
                                               conservation of the Texas hornshell,                    INFORMATION CONTACT. We will schedule                 December 24, 2015). On May 11, 2004,
                                               should be included in a critical habitat                public hearings on this proposal, if any              we were petitioned to list the Texas
                                               designation and why;                                    are requested, and announce the dates,                hornshell, although no new information
                                                  (c) Special management                               times, and places of those hearings, as               was provided in the petition. Because
                                               considerations or protection that may be                well as how to obtain reasonable                      we had already found the species
                                               needed for the essential features in                    accommodations, in the Federal                        warranted listing, no further action was
                                               potential critical habitat areas, including             Register and local newspapers at least                taken on the petition.
                                               managing for the potential effects of                   15 days before the hearing.                              On September 9, 2011, the Service
                                               climate change; and                                     Peer Review                                           entered into two settlement agreements
                                                  (d) What areas not occupied at the                                                                         regarding species on the candidate list
                                               time of listing are essential for the                     In accordance with our joint policy on              at that time (Endangered Species Act
                                               conservation of the species and why.                    peer review published in the Federal                  Section 4 Deadline Litigation, No. 10–
                                                  Please include sufficient information                Register on July 1, 1994 (59 FR 34270),               377 (EGS), MDL Docket No. 2165
                                               with your submission (such as scientific                we will seek the expert opinions of five              (D.D.C. May 10, 2011)). This proposed
                                               journal articles or other publications) to              appropriate and independent specialists
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                                                                                                                                                             listing rule fulfills the requirements of
                                               allow us to verify any scientific or                    regarding this proposed rule. The                     those settlement agreements for the
                                               commercial information you include.                     purpose of peer review is to ensure that              Texas hornshell.
                                                  Please note that submissions merely                  our listing determination is based on
                                               stating support for or opposition to the                scientifically sound data, assumptions,               Background
                                               action under consideration without                      and analyses. We invite comment from                     A thorough review of the taxonomy,
                                               providing supporting information,                       the peer reviewers during the public                  life history, ecology, and overall
                                               although noted, will not be considered                  comment period on this proposed rule.                 viability of the Texas hornshell


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                                               52798               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               (Popenaias popeii) is presented in the                  ready for release. These mature larvae,               individuals were captured and marked
                                               Species Status Assessment Report for                    called glochidia, are obligate parasites              in the Black River in New Mexico in
                                               the Texas Hornshell (SSA report)                        (cannot live independently of their                   1997, and were recaptured 15 years later
                                               (Service 2016; available at http://                     hosts) on the gills, head, or fins of fishes          (Inoue et al. 2014, p. 5). Species in the
                                               www.regulations.gov). The SSA report                    (Vaughn and Taylor 1999, p. 913).                     subfamily Ambleminae, which includes
                                               documents the results of the                            Glochidia die if they fail to find a host             Texas hornshell, commonly live more
                                               comprehensive biological status review                  fish, attach to a fish that has developed             than 20 years (Carman 2007, p. 9), so we
                                               for the Texas hornshell and provides an                 immunity from prior infestations, or                  assume the Texas hornshell can live at
                                               account of the species’ overall viability               attach to the wrong location on a host                least 20 years.
                                               through forecasting of the species’                     fish (Neves 1991, p. 254; Bogan 1993, p.
                                                                                                                                                                Little is known about the specific
                                               condition in the future (Service 2016,                  599). Glochidia encyst (enclose in a
                                                                                                                                                             feeding habits of Texas hornshell. Like
                                               entire). In the SSA report, we                          cyst-like structure) on the host’s tissue,
                                                                                                                                                             all adult freshwater mussels, Texas
                                               summarized the relevant biological data                 draw nutrients from the fish, and
                                               and a description of past, present, and                 develop into juvenile mussels weeks or                hornshell are filter feeders, siphoning
                                               likely future stressors and conducted an                months after attachment (Arey 1932, pp.               suspended phytoplankton and detritus
                                               analysis of the viability of the species.               214–215).                                             from the water column (Yeager et al.
                                               The SSA report provides the scientific                     For the Texas hornshell, spawning                  1994, p. 221; Carman 2007, p. 8).
                                               basis that informs our regulatory                       generally occurs from March through                   Habitat and Range
                                               decision regarding whether this species                 August (Smith et al. 2003, p. 335), and
                                               should be listed as an endangered or                    fertilized eggs are held in the marsupial                Adult Texas hornshell occur in
                                               threatened species under the Act. This                  chambers of females for 4 to 6 weeks                  medium to large rivers, in habitat not
                                               decision involves the application of                    (Smith et al. 2003, p. 337). Glochidia are            typical for most mussel species: In
                                               standards within the Act, its                           released in a sticky mucous net or string             crevices, undercut riverbanks, travertine
                                               implementing regulations, and Service                   (Carman 2007, p. 9); the host fish likely             shelves, and under large boulders
                                               policies (see Determination, below). The                swim into the nets, and the glochidia                 adjacent to runs (Carman 2007, p. 6;
                                               SSA report contains the risk analysis on                generally attach to the face or gills of the          Randklev et al. 2015, p. 8), although in
                                               which this determination is based, and                  fish and become encysted in its tissue                the Devils River, the species is found in
                                               the following discussion is a summary                   (Levine et al. 2012, pp. 1858). The                   gravel beds at the heads of riffles and
                                               of the results and conclusions from the                 glochidia will remain encysted for about              rapids (Randklev et al. 2015, p. 8).
                                               SSA report. We solicited peer review of                 a month through transformation to the                 Small-grained material, such as clay,
                                               the draft SSA report from five qualified                juvenile stage. Once transformed, the                 silt, or sand, gathers in these crevices
                                               experts. We received responses from                     juveniles will excyst from the fish and               and provides suitable anchoring
                                               four of the reviewers, and we modified                  drop to the substrate. The known                      substrate. These crevices are considered
                                               the SSA report as appropriate.                          primary host fishes for the Texas                     to be flow refuges from the large flood
                                                                                                       hornshell are river carpsucker                        events that occur regularly in the rivers
                                               Species Description                                     (Carpiodes carpio), grey redhorse                     this species occupies. Texas hornshell
                                                  The Texas hornshell is a medium                      (Moxostoma congestum), and red shiner                 are able to use these flow refuges to
                                               sized (3 to 4 inches long) freshwater                   (Cyprinella lutrensis) (Levine et al.                 avoid being swept away as large
                                               mussel with a dark brown to green,                      2012, pp. 1857–1858).                                 volumes of water move through the
                                               elongate, laterally compressed shell                       Mussels are generally immobile but
                                                                                                                                                             system, as there is relatively little
                                               (Howells et al. 1996, p. 93; Carman                     experience their primary opportunity
                                                                                                                                                             particle movement in the flow refuges,
                                               2007, p. 2). The Texas hornshell was                    for dispersal and movement within the
                                                                                                                                                             even during flooding (Strayer 1999, p.
                                               described by Lea (1857, p. 102) from the                stream as glochidia attached to a mobile
                                                                                                                                                             472). Texas hornshell are not known
                                               Devils River in Texas and Rio Salado in                 host fish (Smith 1985, p. 105). Upon
                                                                                                                                                             from lakes, ponds, or reservoirs.
                                               Mexico. Currently, the Texas hornshell                  release from the host, newly
                                               is classified in the unionid subfamily                  transformed juveniles drop to the                        The Texas hornshell historically
                                               Ambleminae (Campbell et al. 2005, pp.                   substrate on the bottom of the stream.                ranged throughout the Rio Grande
                                               140, 144) and is considered a valid                     Those juveniles that drop in unsuitable               drainage in the United States (New
                                               taxon by the scientific community                       substrates die because their immobility               Mexico and Texas) and Mexico as well
                                               (Turgeon et al. 1998, p. 36).                           prevents them from relocating to more                 as Mexican Gulf Coast streams south to
                                                  Freshwater mussels, including the                    favorable habitat. Juvenile freshwater                the northern Mexican state of Veracruz
                                               Texas hornshell, have a complex life                    mussels burrow into interstitial                      (Johnson 1999, p. 23). Currently, five
                                               history. Males release sperm into the                   substrates and grow to a larger size that             known populations of Texas hornshell
                                               water column, which are taken in by the                 is less susceptible to predation and                  remain in the United States: Black River
                                               female through the incurrent siphon                     displacement from high flow events                    (Eddy County, New Mexico), Pecos
                                               (the tubular structure used to draw                     (Yeager et al. 1994, p. 220). Throughout              River (Val Verde County, Texas), Devils
                                               water into the body of the mussel). The                 the rest of their life cycle, mussels                 River (Val Verde County, Texas), Lower
                                               sperm fertilizes the eggs, which are held               generally remain within the same small                Canyons of the Rio Grande (Brewster
                                               during maturation in an area of the gills               area where they excysted from the host                and Terrell Counties, Texas), and Lower
                                               called the marsupial chamber. The                       fish.                                                 Rio Grande near Laredo (Webb County,
                                               developing larvae remain in the gill                       Life span is not known for the Texas               Texas) (Map 1). They are described
                                               chamber until they mature and are                       hornshell, although two adult                         briefly below.
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                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                           52799




                                                  Black River: The Black River, in Eddy                   Pecos River: In the Pecos River,                   about the population. The population
                                               County, New Mexico, originates from                     inundation from Amistad Reservoir has                 appears to be extremely small, and no
                                               several groundwater-fed springs and                     resulted in the extirpation of Texas                  evidence of reproduction was noted.
                                               flows approximately 30 miles (mi) (48                   hornshell from the lower reaches of the                  Devils River: Texas hornshell were
                                               kilometers (km)) through the                            river. Additionally, salinity levels are              historically found in the Devils River
                                               Chihuahuan Desert until its confluence                  too high for freshwater mussel                        and were known to occupy only the
                                               with the Pecos River (Inoue et al. 2014,                habitation in much of the Pecos River                 lower reaches of the river, which are
                                               p. 3) near Malaga, New Mexico.                          from the confluence with the Black                    currently inundated by Amistad
                                               Extensive population monitoring (Lang                   River in New Mexico, downstream to                    Reservoir (Neck 1984, p. 11; Johnson
                                               2001, entire; 2006, entire; 2010, entire;               the confluence with Independence                      1999, p. 23; Burlakova and Karatayev
                                               2011, entire) and a long-term mark-                     Creek. However, three live Texas                      2014, p. 19). In recent years, 11
                                               recapture study (Inoue et al. 2014,                     hornshell were collected from a small                 individuals were collected from
                                                                                                       section of the Pecos River downstream                 upstream in the Devils River between
                                               entire) have yielded significant
                                                                                                       of the confluence with Independence                   2008 and 2014 (Burlakova and
                                               information about the population size
                                                                                                       Creek and upstream of Amistad                         Karatayev 2014, p. 16; Karatayev et al.
                                               and extent. Texas hornshell occur in                    Reservoir near Pandale in Val Verde
                                               approximately 8.7 mi (14.0 km) of the                                                                         2015, p. 4). More intensive surveys
                                                                                                       County, Texas, as well as 37 shells                   conducted in 2014 and 2015, including
                                               middle Black River, between two low-                    (Bosman et al. 2016, p. 6; Randklev et
                                               head (small) dams (Lang 2001, p. 20).                                                                         11 sites, have yielded 48 individuals at
                                                                                                       al. 2016, p. 9). Farther downstream,                  two sites: All from The Nature
                                               The total population size has been                      only dead shells were found in 2016,                  Conservancy’s Dolan Falls Preserve
                                               estimated at approximately 48,000                       although they were numerous (Bosman                   except for a singleton at the Devils River
                                               individuals (95 percent confidence                      et al. 2016, p. 6; Randklev et al. 2016,              State Natural Area’s Dan A. Hughes Unit
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                                               interval: 28,849–74,127) (Inoue et al.                  p. 9). Live individuals had not been                  (formerly known as the Big Satan Unit)
                                               2014, p. 7), with a diversity of size                   collected at this location since 1973                 (Randklev et al. 2015, pp. 6–7). Because
                                               classes, primarily aggregated in flow                   (Randklev et al. 2016, p. 4).                         of the increased number of individuals
                                               refuges within narrow riffles. The                         Because the sample size of live                    collected in 2014 and 2105, it is likely
                                               population remained relatively stable                   individuals is so small (three live                   that the Devils River population is more
                                               over the 15 year study period from 1997                 individuals found in recent months), it               numerous than previously thought,
                                               to 2012 (Inoue et al. 2014, p. 6).
                                                                                                                                                                                                          EP10AU16.000</GPH>




                                                                                                       is difficult to draw many conclusions                 although we do not expect that this


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                                               52800               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               population is particularly large based on               (Randklev et al. 2015, p. 7). Throughout              redundancy, and representation, we
                                               the limited number of collections to                    this reach, the density of Texas                      describe the species’ level of viability
                                               date. Interestingly, Texas hornshell in                 hornshell is estimated 170 ± 131                      over time. For the Texas hornshell to
                                               the Devils River occupy different                       individuals per suitable (rocky) habitat              maintain viability, its populations or
                                               habitats than those in the rest of the                  site (Randklev et al. 2015, p. 7). Young              some portion thereof must be resilient.
                                               range; instead of being found under rock                individuals and gravid females have                   A number of factors influence the
                                               slabs and in travertine shelves, they                   been found throughout the Laredo                      resiliency of Texas hornshell
                                               occupy gravel beds at the heads of riffles              reach, indicating reproduction and                    populations, including occupied stream
                                               or in clean-swept pools with bedrock                    recruitment are occurring (Randklev et                length, abundance, and recruitment.
                                               (Randklev et al. 2015, p. 8). Even though               al. 2015, p. 8). No live Texas hornshell              Elements of Texas hornshell habitat that
                                               the number of collected individuals is                  have been found downstream of the city                determine whether Texas hornshell
                                               small, several young individuals were                   of Laredo in recent years.                            populations can grow to maximize
                                               found, as well as females brooding                         Mexico: A large portion of the Texas               habitat occupancy influence those
                                               glochidia (gravid females) (Randklev et                 hornshell’s estimated historical range is             factors, thereby increasing the resiliency
                                               al. 2015, p. 8), indicating reproduction                in Mexico. The species occurred in the                of populations. These resiliency factors
                                               and recruitment (offspring survive to                   Rio Salado basin, which is a tributary to             and habitat elements are discussed here.
                                               join the reproducing population) are                    the Rio Grande in Mexico, and in                         Occupied Stream Length: Most
                                               occurring in the Devils River                           approximately 15 rivers that flow into                freshwater mussels, including Texas
                                               population.                                             the Gulf of Mexico. At one time, one-                 hornshell, are found in aggregations,
                                                  Rio Grande—Lower Canyons: One of                     half to two-thirds of the species’ range              called mussel beds, that vary in size
                                               two remaining populations of Texas                      may have been in Mexico.                              from about 50 to greater than 5,000
                                               hornshell in the Rio Grande is found in                 Unfortunately, the most recent live                   square meters (m2) (540 to greater than
                                               the Lower Canyons, just downstream of                   collections of Texas hornshell in Mexico              53,800 square feet (ft2)), separated by
                                               Big Bend National Park, in Terrell                      occurred in the 1980s (Mussel Project                 stream reaches in which mussels are
                                               County, Texas. Burlakova and Karatayev                  2015, entire), and we have very few                   absent or rare (Vaughn 2012, p. 983).
                                               (2014, p. 16) found the species in low                  records of surveys with positive or                   Resilient Texas hornshell populations
                                               density (approximately 40 individuals                   negative collection data since that time.             must occupy stream reaches sufficient
                                               per km) in this region of the Rio Grande.               We have no information on population                  in length such that stochastic events
                                               Subsequent surveys by Randklev et al.                   size or extent during those times of                  that affect individual mussel beds do
                                               (2015, entire) confirmed the presence of                collection, and we also have no                       not eliminate the entire population.
                                               Texas hornshell in approximately 18.5                   information on whether populations of                 Repopulation by fish infested with
                                               mi (30 km) of the Lower Canyons in two                  Texas hornshell still occur in one or                 Texas hornshell glochidia from other
                                               sections, finding that the species                      more of these streams; therefore, we                  mussel beds within the reach, if present
                                               occupies approximately 63 percent of                    have very low confidence in the species’              and connected, can allow the
                                               sites with suitable (rocky) habitat. For                current condition throughout most of                  population to recover from these events.
                                               purposes of this analysis, we presume                   the Mexican range. One or more of these                  Abundance: Mussel abundance in a
                                               the entire section between these                        populations may still be extant, or they              given stream reach is a product of the
                                               collections, approximately 62 mi (100                   may all be extirpated.                                number of mussel beds times the
                                               km), is occupied. Sites in the Rio                                                                            density of mussels within those beds.
                                                                                                       Species Needs                                         For populations of Texas hornshell to be
                                               Grande—Lower Canyons reach vary in
                                               density, with the densest sites near                       Texas hornshell need seams of fine                 resilient, there must be many mussel
                                               Sanderson Canyon, Terrell County,                       sediment in crevices, undercut                        beds of sufficient density (∼200
                                               Texas, and decreasing downstream                        riverbanks, travertine shelves, and large             individuals per 150 m2 (1,614 ft2); see
                                               (Randklev et al. 2015, p. 13); the average              boulders in riverine ecosystems with                  SSA report for more discussion) such
                                               density of Texas hornshell at each site                 flowing water and periodic cleansing                  that local stochastic events do not
                                               is lower compared to the Black River                    flows to keep the substrate free of fine              necessarily eliminate the bed(s),
                                               and Rio Grande—Laredo (5 ± 14                           sediment accumulation. They need                      allowing the mussel bed and the overall
                                               individuals per site). Texas hornshell                  water quality parameters to be within a               population in the stream reach to
                                               may occur between the known occupied                    suitable range (i.e., dissolved oxygen                recover from any one event. We measure
                                               sections, near the confluence with San                  above 3 milligrams/liter (mg/L), salinity             Texas hornshell abundance by the
                                               Francisco Creek (Howells 2001a, p. 6),                  below 0.9 parts per thousand, and                     number of beds within the population,
                                               but limited access has prevented recent                 ammonia below 0.7 mg/L (Sparks and                    and the estimated density of Texas
                                               surveys from determining current                        Strayer 1998, p. 132; Augspurger et al.               hornshell within each.
                                               occupancy of this reach. Young                          2003, p. 2574; Augspurger et al. 2007, p.                Reproduction: Resilient Texas
                                               individuals and gravid females have                     2025; Carman 2007, p. 6)) and                         hornshell populations must also be
                                               been found throughout the Lower                         phytoplankton as food. Finally, Texas                 reproducing and recruiting young
                                               Canyons reach, indicating recruitment is                hornshell need host fish to be present                individuals into the reproducing
                                               occurring (Randklev et al. 2015, p. 8).                 during times of spawning.                             population. Population size and
                                                  Rio Grande—Laredo: The largest                          We describe the Texas hornshell’s                  abundance reflects previous influences
                                               Texas hornshell population occurs from                  viability by characterizing the status of             on the population and habitat, while
                                               Laredo, Texas (near La Bota Ranch just                  the species in terms of its resiliency                reproduction and recruitment reflect
                                               northwest of Laredo), upstream                          (ability of the populations to withstand              population trends that may be stable,
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                                               approximately 56 mi (90 km) (Randklev                   stochastic events), redundancy (ability               increasing, or decreasing. Detection of
                                               et al. 2015, p. 7). The density in this                 of the species to withstand large-scale,              very young juvenile mussels during
                                               reach is high, with some habitat patches                catastrophic events), and representation              routine abundance and distribution
                                               containing more than 8,000 individuals                  (the ability of the species to adapt to               surveys happens extremely rarely due to
                                               (Karatayev et al. 2015, p. 4) and 100                   changing environmental conditions).                   sampling bias; sampling for this species
                                               percent of surveyed patches of suitable                 Using various time frames and the                     involves tactile searches, and mussels
                                               habitat containing Texas hornshell                      current and projected resiliency,                     below about 35 millimeters (mm) (1.4


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                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                            52801

                                               inches (in)) are very hard to detect.                   extirpated. As such, maintaining the                  Increased Fine Sediment
                                               Therefore, reproduction is verified by                  remaining representation in the form of
                                               repeatedly capturing small-sized                        genetic diversity may be important to                    Texas hornshell require seams of fine
                                               individuals near the low end of the                     the capacity of the Texas hornshell to                sediment under boulders and bedrock
                                               detectable range size (about 35 mm (1.4                 adapt to future environmental change.                 and in streambanks in order to anchor
                                               in)) over time and by capturing gravid                                                                        themselves into place on the stream
                                                                                                          Finally, the Texas hornshell needs to              bottom; however, too much fine
                                               females during the reproductively active                have multiple resilient populations
                                               time of year (generally, March through                                                                        sediment can fill in these crevices and
                                                                                                       distributed throughout its range to                   smother any mussels within those
                                               August (Smith et al. 2003, p. 335)).
                                                                                                       provide for redundancy, the ability of                spaces. Under natural conditions, fine
                                                  Substrate: Texas hornshell occur in
                                               flow refuges such as crevices, undercut                 the species to withstand catastrophic                 sediments collect on the streambed and
                                               riverbanks, travertine shelves, and large               events. The more populations, and the                 in crevices during low flow events, and
                                               boulders. These refuges must have                       wider the distribution of those                       they are washed downstream during
                                               seams of clay or other fine sediments                   populations, the more redundancy the                  high flow events (also known as
                                               within which the mussels may anchor,                    species will exhibit. Redundancy                      cleansing flows). However, the
                                               but not so much excess sediment that                    reduces the risk that a large portion of              increased frequency of low flow events
                                               the mussels are smothered. Those areas                  the species’ range will be negatively                 (from groundwater extraction, instream
                                               with clean-swept substrate with seams                   affected by a catastrophic natural or                 surface flow diversions, and drought),
                                               of fine sediments are considered to have                anthropogenic event at a given point in               combined with a decrease in cleansing
                                               suitable substrate, and those with                      time. Species that are well-distributed               flows (from reservoir management and
                                               copious fine sediment both in crevices                  across their historical range are                     drought), has caused sediment to
                                               and on the stream bottom are                            considered less susceptible to extinction             accumulate to some degree at all
                                               considered less suitable.                               and have higher viability than species                populations. When water velocity
                                                  Flowing Water: Texas hornshell need                  confined to a small portion of their                  decreases, which can occur from
                                               flowing water for survival. They are not                range (Carroll et al. 2010, entire;                   reduced streamflow or inundation,
                                               found in lakes or in pools without flow,                Redford et al. 2011, entire).                         water loses its ability to carry sediment
                                               or in areas that are regularly dewatered.                                                                     in suspension; sediment falls to the
                                                                                                       Summary of Biological Status and
                                               River reaches with continuous flow are                                                                        substrate, eventually smothering
                                               considered suitable habitat, while those                Threats
                                                                                                                                                             mussels that cannot adapt to soft
                                               with little or no flow are considered not                 The Act directs us to determine                     substrates (Watters 2000, p. 263).
                                               suitable.                                               whether any species is an endangered                  Sediment accumulation can be
                                                  Water Quality: Freshwater mussels, as                species or a threatened species because               exacerbated when there is a
                                               a group, are sensitive to changes in                    of any factors affecting its continued                simultaneous increase in the sources of
                                               water quality parameters such as                        existence. We completed a                             fine sediments in a watershed. In the
                                               dissolved oxygen, salinity, ammonia,                    comprehensive assessment of the                       range of Texas hornshell, these sources
                                               and pollutants (i.e., dissolved oxygen                                                                        include streambank erosion from
                                                                                                       biological status of the Texas hornshell,
                                               above 3 mg/L, salinity below 0.9 parts                                                                        agricultural activities, livestock grazing,
                                                                                                       and prepared a report of the assessment,
                                               per thousand, and ammonia below 0.7                                                                           and roads, among others.
                                                                                                       which provides a thorough account of
                                               mg/L (Sparks and Strayer 1998, p. 132;
                                                                                                       the species’ overall viability. In this                  Interstitial spaces (small openings
                                               Augspurger et al. 2003, p. 2574;
                                                                                                       section, we summarize the conclusions                 between rocks and gravels) in the
                                               Augspurger et al. 2007, p. 2025; Carman
                                                                                                       of that assessment, which can be                      substrate provide essential habitat for
                                               2007, p. 6)). Habitats with appropriate
                                                                                                       accessed at Docket No. FWS–R2–ES–                     juvenile mussels. Juvenile freshwater
                                               levels of these parameters are
                                                                                                       2016–0077 on http://                                  mussels burrow into interstitial
                                               considered suitable, while those
                                                                                                       www.regulations.gov.                                  substrates, making them particularly
                                               habitats with levels outside of the
                                               appropriate ranges are considered less                                                                        susceptible to degradation of this habitat
                                                                                                       Risk Factors
                                               suitable.                                                                                                     feature. When clogged with sand or silt,
                                                  Maintaining representation in the                       We reviewed the potential risk factors             interstitial flow rates and spaces may
                                               form of genetic or ecological diversity is              (i.e., threats, stressors) that could be              become reduced (Brim Box and Mossa
                                               important to maintain the Texas                         affecting the Texas hornshell now and                 1999, p. 100), thus reducing juvenile
                                               hornshell’s capacity to adapt to future                 in the future. In this proposed rule, we              habitat availability.
                                               environmental changes. Texas hornshell                  will discuss only those factors in detail                All populations of Texas hornshell
                                               populations in the Rio Grande and                       that could meaningfully impact the                    face the risk of fine sediment
                                               Devils River (and, presumably, the                      status of the species. Those risks that are           accumulation to varying degrees.
                                               Pecos River, due to its proximity to Rio                not known to have effects on Texas                    Elimination of Texas hornshell from
                                               Grande populations) have distinct                       hornshell populations, such as                        mussel beds due to large amounts of
                                               variation in allele frequencies from                    collection and disease, are not discussed             sediment deposition has been
                                               those in the Black River (Inoue et al.                  here. The primary risk factors (i.e.,                 documented on the Black River in two
                                               2015, p. 1916). We expect additional                    threats) affecting the status of the Texas            locations in recent years. In the future,
                                               variation was present in Mexican                        hornshell are: (1) Increased fine                     we expect this may continue to occur
                                               populations. Mussels, like Texas                        sediment (Factor A from the Act), (2)                 sporadically. Fine sediments are also
                                               hornshell, need to retain populations                   water quality impairment (Factor A), (3)              accumulating at the Rio Grande—Laredo
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                                               throughout their range to maintain the                  loss of flowing water (Factor A), (4)                 population. Low water levels on the
                                               overall potential genetic and life-history              barriers to fish movement (Factor E),                 Devils River will likely lead to
                                               attributes that can buffer the species’                 and (5) increased predation (Factor C).               additional sediment accumulation at
                                               response to environmental changes over                  These factors are all exacerbated by                  this population, as well. In the future,
                                               time (Jones et al. 2006, p. 531). The                   climate change. Finally, we reviewed                  we expect lower flows to occur more
                                               Texas hornshell has likely lost genetic                 the conservation efforts being                        often at all populations and for longer
                                               diversity as populations have been                      undertaken for the species.                           periods due to climate change.


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                                               52802               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               Water Quality Impairment                                downstream of the Texas hornshell                     in the constantly cold hypolimnion
                                                  Water quality can be impaired                        population has had salinity levels in the             (deepest portion of the reservoir) in
                                               through contamination or alteration of                  range of 6 ppm, which may be one                      these reservoirs may never reproduce, or
                                               water chemistry. Chemical                               reason the population has been                        reproduce less frequently. Additionally,
                                               contaminants are ubiquitous throughout                  extirpated from the downstream reach.                 the effects of these reservoirs extend
                                               the environment and are a major reason                     Contaminant spills are also a concern.             beyond inundation and fragmentation of
                                               for the current declining status of                     In particular, the Black River population             populations; the reservoirs are managed
                                               freshwater mussel species nationwide                    is vulnerable to spills from the high                 for flood control and water delivery, and
                                               (Augspurger et al. 2007, p. 2025).                      volume of truck traffic crossing the river            the resultant downstream releases rarely
                                               Chemicals enter the environment                         at low water access points (Bren School               mimic natural flow regimes, tempering
                                                                                                       of Environmental Management 2014, p.                  the natural fluctuations in flow that
                                               through both point and nonpoint
                                                                                                       26). Due to the topography and steep                  flush fine sediments from the substrate.
                                               discharges, including spills, industrial
                                                                                                       slopes of these areas, spilled                           At the Rio Grande—Laredo
                                               sources, municipal effluents, and
                                                                                                       contaminants and contaminated soils                   population, a low-water weir has been
                                               agricultural runoff. These sources
                                                                                                       could directly enter the surface water of             proposed for construction (Rio Grande
                                               contribute organic compounds, heavy
                                                                                                       the river and negatively impact the                   Regional Water Planning Group 2016, p.
                                               metals, pesticides, herbicides, and a
                                                                                                       species (Boyer 1986, p. 300) and                      8–8). The dam would be located just
                                               wide variety of newly emerging
                                                                                                       downstream habitat. For the smaller                   downstream of the La Bota area, which
                                               contaminants to the aquatic
                                                                                                       populations (Black, Devils, Pecos                     contains the largest known and most
                                               environment. Ammonia is of particular                                                                         dense Texas hornshell bed within the
                                                                                                       rivers), a single spill could eliminate the
                                               concern below water treatment plants                    entire population.                                    Rio Grande—Laredo population and
                                               because freshwater mussels have been                       A reduction in surface flow from                   rangewide. The impounded area would
                                               shown to be particularly sensitive to                   drought, instream diversion, or                       extend approximately 14 mi (22.5 km)
                                               increased ammonia levels (Augspurger                    groundwater extraction concentrates                   upstream, effectively eliminating habitat
                                               et al. 2003, p. 2569). It is likely for this            contaminant and salinity levels,                      for Texas hornshell from 25 percent of
                                               reason that Texas hornshell are not                     increases water temperatures in streams,              the currently occupied area and likely
                                               found for many miles downstream of                      and exacerbates effects to Texas                      leading to extirpation of the densest
                                               two wastewater treatment plants that                    hornshell.                                            sites within this population.
                                               discharge into the Rio Grande: at Nuevo                    Poor water quality affects most Texas                 Very low water levels are detrimental
                                               Laredo, Mexico, and at Eagle Pass,                      hornshell populations currently to some               to Texas hornshell populations, as well.
                                               Texas (Karatayev et al. 2015, p. 14).                   degree, and future water quality is                   Effects of climate change have already
                                                  An additional type of water quality                  expected to decrease due to decreasing                begun to affect the regions of Texas and
                                               impairment is alteration of water quality               river flow and increasing temperatures.               New Mexico where the Texas hornshell
                                               parameters such as dissolved oxygen,                    The Pecos River experiences very high                 occurs, resulting in higher air
                                               temperature, and salinity levels.                       salinity levels upstream of the existing              temperatures, increased evaporation,
                                               Dissolved oxygen levels may be reduced                  population, and we expect that the                    increased groundwater pumping, and
                                               from increased nutrients in the water                   observed high mortality of the Pecos                  changing precipitation patterns such
                                               column from runoff or wastewater                        River population is due to salinity                   that water levels rangewide have
                                               effluent, and juveniles seem to be                      pulses. Rangewide, as water flow is                   already reached historic lows (Dean and
                                               particularly sensitive to low dissolved                 expected to decrease due to climate                   Schmidt 2011, p. 336; Bren School of
                                               oxygen (Sparks and Strayer 1998, pp.                    change, water quality will decline.                   Environmental Management 2014, p.
                                               132–133). Increased water temperature                                                                         50). The rivers inhabited by Texas
                                               from climate change and from low flows                  Loss of Flowing Water
                                                                                                                                                             hornshell have some resiliency to
                                               during drought can exacerbate low                          Texas hornshell populations need                   drought because they are spring-fed
                                               dissolved oxygen levels as well as have                 flowing water in order to survive. Low                (Black and Devils Rivers) and very large
                                               its own effects on both juvenile and                    flow events (including stream drying)                 (Rio Grande), but drought in
                                               adult mussels. Finally, salinity appears                and inundation can eliminate                          combination with increased
                                               to be particularly limiting to Texas                    appropriate habitat for Texas hornshell,              groundwater pumping and regulated
                                               hornshell. The aquifer near Malaga,                     and while the species can survive these               reservoir releases may lead to lower
                                               New Mexico, contains saline water. As                   events if they last for a short time,                 river flows of longer duration than have
                                               the saline water emerges from the                       populations that experience these                     been recorded in the past. Streamflow in
                                               ground, it is diluted by surface flow. As               events regularly will not persist.                    the Rio Grande downstream of the
                                               surface flow decreases, however, the                       Inundation has primarily occurred                  confluence with the Rio Conchos (near
                                               concentration of salinity in the river                  upstream of dams, both large (such as                 the Rio Grande-Lower Canyons
                                               increases. Additionally, aquifers have                  Amistad, Falcon, and Red Bluff Dams)                  population) has been declining since the
                                               become increasingly saline due to                       and small (low water crossings and                    1980s (Miyazono et al. 2015, p. A–3),
                                               salinized water recharge (Hoagstrom                     diversion dams, such as those on the                  and overall river discharge for the Rio
                                               2009, p. 35). Irrigation return flows                   Black River). Inundation causes an                    Grande is projected to continue to
                                               exacerbate salinity levels as salts build               increase in sediment deposition,                      decline due to increased drought as a
                                               up on irrigated land and then are                       eliminating the crevices this species                 result of climate change (Nohara et al.
                                               washed into the riverway. The Pecos                     inhabits. In large reservoirs, deep water             2006, p. 1087). The Rio Conchos
                                               River from the confluence with the                      is very cold and often devoid of oxygen               contributes more than 90 percent of the
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                                               Black River to the confluence with                      and necessary nutrients. Cold water                   flow of the lower Rio Grande (Dean and
                                               Independence Creek has become                           (less than 11 degrees Celsius (°C) (52                Schmidt 2011, p. 4). However, during
                                               particularly saline in the past few                     degrees Fahrenheit (°F))) has been                    times of drought (such as between 1994
                                               decades, with levels at 7 parts per                     shown to stunt mussel growth (Hanson                  and 2003), Mexico has fallen short of its
                                               million (ppm) or higher, which is too                   et al. 1988, p. 352). Because glochidial              water delivery commitments, and so the
                                               high for freshwater mussel habitation.                  release may be temperature dependent,                 contribution of the Rio Conchos has
                                               Additionally, the Black River                           it is likely that relict individuals living           fallen to as low as 40 percent (Carter et


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                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                           52803

                                               al. 2015, p. 15). The Rio Grande—Lower                  Barriers to Fish Movement                             pose a significant risk to any given
                                               Canyons population is downstream of                       Two of the Texas hornshell’s primary                population. However, during periods of
                                               the confluence with the Rio Conchos                     host fish species (river carpsucker and               low flow, terrestrial predators have
                                               and is at risk from these reduced                       red shiner) are known to be common,                   increased access to portions of the river
                                               deliveries. The Rio Grande—Lower                        widespread species. We do not expect                  that are otherwise too deep under
                                               Canyons is very incised (in other words,                the distribution of host fish to be a                 normal flow conditions. High levels of
                                               has vertical banks), and the population                 limiting factor in Texas hornshell                    predation during drought have been
                                               occurs in crevices along the steep banks.               distribution. However, the barriers that              observed on the Devils River, and
                                               Due to the habitat characteristics of this                                                                    muskrat predation has also been
                                                                                                       prevent fish movement upstream and
                                               population, reductions in discharge in                                                                        reported on the Black River. As drought
                                                                                                       downstream affect the viability of Texas
                                               this area may lead to a higher                                                                                and low flow conditions are predicted
                                                                                                       hornshell.
                                               proportion of the Texas hornshell                                                                             to occur more often and for longer
                                                                                                         Texas hornshell were likely
                                               population being exposed than would                                                                           periods due to the effects of climate
                                                                                                       historically distributed throughout the
                                               be found in other populations                                                                                 change, the Black and Devils Rivers are
                                                                                                       Rio Grande, Pecos River, Devils River,
                                               experiencing similar flow decreases.                                                                          expected to experience additional
                                                                                                       and Black River in Texas and New
                                                                                                                                                             predation pressure into the future.
                                                  In the Black River, surface water is                 Mexico, as well as throughout the rivers
                                                                                                                                                             Predation is expected to be less of a
                                               removed from the river for irrigation,                  draining to the Gulf of Mexico from
                                                                                                                                                             concern for the Rio Grande populations,
                                               including the Carlsbad Irrigation                       which the species was known when few
                                                                                                                                                             as the river is significantly larger than
                                               District’s Black River Canal at the                     natural barriers existed to prevent
                                                                                                                                                             the Black and Devils Rivers and Texas
                                               diversion dam. Studies have shown that                  migration (via host species) among
                                                                                                                                                             hornshell are less likely to be found in
                                               flows in the river are affected by                      suitable habitats. The species colonized              exposed or very shallow portions of the
                                               groundwater withdrawals, particularly                   new areas through movement of infested                stream.
                                               those from the Black River Valley.                      host fish, and newly metamorphosed
                                               Groundwater in the Black River                          juveniles would excyst from host fish in              Effects of Climate Change
                                               watershed is also being used for                        new locations. Today, the remaining                      Climate change in the form of the
                                               hydraulic fracturing for oil and gas                    populations are significantly isolated                change in timing and amount of
                                               activities. Between 4.3 acre-feet                       from one another such that                            precipitation and air temperature
                                               (187,308 ft3 (5,304 m3)) and 10.7 acre-                 recolonization of areas previously                    increase is occurring, and continued
                                               feet (466,091 ft3 (13,198 m3)) of water is              extirpated is extremely unlikely if not               greenhouse gas emissions at or above
                                               used for each hydraulic fracturing job                  impossible due to existing                            current rates will cause further warming
                                               (Bren School of Environmental                           contemporary barriers to host fish                    (Intergovernmental Panel on Climate
                                               Management 2014, p. 91). Overall, mean                  movement. The primary reason for this                 Change (IPCC) 2013, pp. 11–12).
                                               monthly discharge has already declined                  isolation is reservoir construction and               Warming in the Southwest is expected
                                               since the mid-1990s, and mean monthly                   unsuitable water quality. The Black                   to be greatest in the summer (IPCC 2013,
                                               temperatures have increased over the                    River is isolated from the rest of the                pp. 11–12), and annual mean
                                               past 100 years (Inoue et al. 2014, p. 7).               populations by high salinity reaches of               precipitation is very likely to decrease
                                               In the Black River, survivorship is                     the Pecos River, as well as Red Bluff                 in the Southwest (Ray et al. 2008, p. 1;
                                               positively correlated with discharge                    Reservoir, and is hundreds of river                   IPCC 2013, pp. 11–12). In Texas, the
                                               (Inoue et al. 2014, p. 9); as mean                      miles from the nearest extant                         number of extreme hot days (high
                                               monthly discharge decreases, we expect                  population. Amistad Reservoir separates               temperatures exceeding 95 °F (35 °C) are
                                               Texas hornshell survivorship to                         the three Texas populations from each                 expected to double by around 2050
                                               decrease, as well. The Black River is                   other, isolating the Rio Grande—Lower                 (Kinniburgh et al. 2015, p. 83), and
                                               expected to lose streamflow in the                      Canyons, Devils River, and Rio                        Texas is considered one of the
                                               future due to air temperature increases,                Grande—Laredo populations. There is                   ‘‘hotspots’’ of climate change in North
                                               groundwater extraction, and reduced                     currently no opportunity for interaction              America; west Texas is an area expected
                                               precipitation.                                          among any of the five extant U.S.                     to show greater responsiveness to the
                                                                                                       populations.                                          effects of climate change (Diffenbaugh et
                                                  In the Devils River, future water                      The overall distribution of mussels is,             al. 2008, p. 3). Even if precipitation and
                                               withdrawals from aquifers that support                  in part, a function of the dispersal of               groundwater recharge remain at current
                                               spring flows in the range of the Texas                  their host fish. Small populations are                levels, increased groundwater pumping
                                               hornshell could result in reduction of                  more affected by this limited                         and resultant aquifer shortages due to
                                               critical spring flows and river drying. In              immigration potential because they are                increased temperatures are nearly
                                               particular, there have been multiple                    susceptible to genetic drift (random loss             certain (Loaiciga et al. 2000, p. 193;
                                               proposals to withdraw water from the                    of genetic diversity) and inbreeding                  Mace and Wade 2008, pp. 662, 664–665;
                                               nearby aquifer and deliver the water to                 depression. At the species level,                     Taylor et al. 2012, p. 3). Increased water
                                               municipalities (e.g., Val Verde Water                   populations that are eliminated due to                temperature can cause stress to
                                               Company 2013, pp. 1–2). To date,                        stochastic events cannot be recolonized               individuals, decrease dissolved oxygen
                                               however, none have been approved.                       naturally, leading to reduced overall                 levels, and increase toxicity of
                                                  As spring flows decline due to                       redundancy and representation.                        contaminants. Effects of climate change,
                                               drought or groundwater lowering from                                                                          such as air temperature increases and an
                                               pumping, habitat for the Texas                          Increased Predation                                   increase in drought frequency and
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                                               hornshell is reduced and could                            Predation on freshwater mussels is a                intensity, have been shown to be
                                               eventually cease to exist. While Texas                  natural ecological interaction. Raccoons,             occurring throughout the range of Texas
                                               hornshell may survive short periods of                  snapping turtles, and fish are known to               hornshell (Kinniburgh et al. 2015, p.
                                               low flow, as low flows persist, mussels                 prey upon Texas hornshell. Under                      88), and these effects are expected to
                                               face oxygen deprivation, increased                      natural conditions, the level of                      exacerbate several of the stressors
                                               water temperature, and, ultimately,                     predation occurring within Texas                      discussed above, such as water
                                               stranding.                                              hornshell populations is not likely to                temperature and flow loss (Wuebbles et


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                                               52804               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               al. 2013, p. 16). As we projected the                   expect the reintroduction effort to                   cleansing flows and increased fine
                                               future condition of the Texas hornshell                 continue over the next several years, but             sediments. The distribution of Texas
                                               and which stressors are likely to occur,                we are not considering the action to                  hornshell in the Black River will remain
                                               we considered climate change to be an                   have been successful to date.                         small, and the risk of a contaminant
                                               exacerbating factor in the increase of                    In Texas, The Nature Conservancy                    spill will remain high, resulting in a
                                               fine sediments, changes in water                        and Texas Parks and Wildlife                          high likelihood that water quality will
                                               quality, and loss of flowing water.                     Department manage lands under their                   become unsuitable and reduce
                                                  Due to the effects of ongoing climate                purview in the Devils River watershed                 abundance of Texas hornshell
                                               change, we expect the frequency and                     for native communities, including Texas               significantly. Therefore, taking into
                                               duration of cleansing flows to decrease,                hornshell. The large amount (over                     account the current threats to the
                                               leading to the increase in fine sediments               200,000 acres) of land in conservation                population and its distribution within
                                               and reduced water levels at all                         management in the Devils River                        the river, the Texas hornshell
                                               populations. More extreme climate                       watershed reduces the risks to Texas                  population in the Black River has low
                                               change projections lead to further                      hornshell from sediment inputs and                    resiliency.
                                               increases in fine sediment within the                   contaminants.                                            Pecos River: The Pecos River
                                               populations. Similarly, as lower water                    In the Rio Grande, we are not aware                 population is extremely small and
                                               levels concentrate contaminants and                     of any management actions for Texas                   exhibits no evidence of reproduction.
                                               cause unsuitable temperature and                        hornshell. The Texas Comptroller of                   The few number of live individuals
                                               dissolved oxygen levels, we expect                      Public Accounts has established an                    among the very high number of dead
                                               water quality to decline to some degree                 Endangered Species Task Force and has                 shells indicates a population in severe
                                               in the future.                                          funded much of the recent research in                 decline; this is likely due to high
                                                                                                       Texas on Texas hornshell, which has                   salinity levels in the river upstream of
                                               Conservation Actions and Regulatory                     led to greater understanding of the                   the population. There is a high
                                               Mechanisms                                              species’ distribution in the State.                   likelihood this population will be
                                                  About 7 percent of known occupied                                                                          extirpated in the near future due to
                                               habitat for the Texas hornshell is in                   Current Condition
                                                                                                                                                             water quality alone. Therefore, the
                                               New Mexico, and the Service is                             Overall, there are five known                      Pecos River population of Texas
                                               collaborating with water users, oil and                 remaining populations of Texas                        hornshell has very low resiliency.
                                               gas developers, landowners, and other                   hornshell, comprising approximately 15                   Devils River: The Devils River
                                               partners to develop candidate                           percent of the species’ historical range              population has low abundance and has
                                               conservation agreements (CCAs) for the                  in the United States (see Map 1, above).              exhibited some evidence of
                                               species on State, Federal, and private                  Historically, most Texas hornshell                    reproduction. The current level of
                                               lands. These agreements are currently                   populations were likely connected by                  climate change will continue to reduce
                                               under development, and the potential                    fish migration throughout the Rio                     flow in the Devils River due to
                                               purpose is to provide voluntary                         Grande, upstream through the Pecos                    groundwater extraction and drought.
                                               conservation that would reduce threats                  River, and throughout the tributaries,                The low flows this population
                                               to the species while improving physical                 but due to impoundments and river                     experiences during dry times will
                                               habitat and water quality. The key                      reaches with unsuitable water quality                 continue to become more frequent and
                                               conservation measures in the                            (for example, high salinity) they are                 prolonged. Because Texas hornshell in
                                               agreements will be designed to limit oil                currently isolated from one another, and              the Devils River occur at the heads of
                                               and gas development to areas outside of                 repopulation of extirpated locations is               riffles, they are vulnerable to complete
                                               the Black and Delaware River                            unlikely to occur without human                       flow loss when water levels drop. The
                                               floodplains, minimize erosion, and                      assistance. Here we discuss the current               reduction in cleansing flows will also
                                               maintain minimum water flows in the                     condition of each known population,                   result in the accumulation of fine
                                               rivers. Along with these measures, the                  taking into account the risks to those                sediments, reducing substrate quality.
                                               partners to the agreement are evaluating                populations that are currently occurring,             Low flows will also affect water quality
                                               alternatives to the multiple low water                  as well as management actions that are                parameters such as temperature and
                                               crossings on the Black River. Partners                  currently occurring to address those                  dissolved oxygen, causing them to
                                               are considering alternate crossing                      risks. We consider low levels of climate              become unsuitable for Texas hornshell.
                                               locations, which could include bridges                  change to be currently occurring,                     Additionally, the species is already
                                               designed to allow host fishes to pass                   resulting in reduced timing and amount                vulnerable to predation from terrestrial
                                               through in addition to decreasing                       of streamflow, increased stream                       predators during times of low flow;
                                               potential contamination events. Because                 temperatures, and increased                           predation will occur more frequently as
                                               these agreements have not been                          accumulation of fine sediments.                       periods of low flow become more
                                               completed, we are not considering the                      Black River: The Black River                       common. Overall, because the
                                               conservation actions in our present                     population is quite dense and                         population is currently small and would
                                               evaluation of the status of Texas                       recruitment appears to be high, but the               be unlikely to grow, the Devils River
                                               hornshell.                                              short size (8.7 mi (14.0 km)) of the                  population has low resiliency.
                                                  The New Mexico Department of Game                    occupied reach limits this population’s                  Rio Grande—Lower Canyons: The
                                               and Fish has begun Texas hornshell                      resiliency. Accumulation of fine                      Lower Canyons population has
                                               reintroduction efforts into the Delaware                sediment in the substrate has already                 relatively high abundance and evidence
                                               River, which is within the historical                   occurred due to increased sediment                    of recruitment. Drought and
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                                               range of the species. Adults and infested               input into the river from road crossings,             groundwater extraction resulting from
                                               host fish were released in suitable                     culverts, and cattle grazing, combined                currently observed levels of climate
                                               habitat in the Delaware River in 2013                   with a decreased frequency of cleansing               change will continue to lower water
                                               and 2015. Many of the released adults                   river flows. The current level of climate             levels in the Rio Grande—Lower
                                               have been subsequently located, and                     change will continue to reduce flow in                Canyons population of Texas hornshell.
                                               success of the reintroduction will be                   the river from groundwater extraction                 We expect that Mexico’s management of
                                               determined in the coming years. We                      and drought, resulting in fewer                       the Rio Conchos will continue to be an


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                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                            52805

                                               unreliable source of water. This section                was determined to be endangered, other                and future threats to the Texas
                                               of the Rio Grande is relatively deep and                projected scenarios would also be                     hornshell. Our analysis of the past,
                                               incised, and the population of Texas                    endangered, as they forecast conditions               current, and future influences on what
                                               hornshell primarily occurs in crevices                  that are more at risk of extinction than              the Texas hornshell needs for long-term
                                               along the banks. Water flow reductions                  the status quo. Please refer to the SSA               viability revealed that there are five
                                               would expose a high proportion of the                   report (Service 2016) for the full                    influences that may pose a meaningful
                                               existing population; therefore, this                    analysis of future scenarios.                         risk to the viability of the species. These
                                               reduction in flow will likely have a                                                                          are primarily related to habitat changes
                                                                                                       Determination
                                               larger effect on the population size than                                                                     (Factor A from the Act): The
                                               in other populations, although at a small                  Section 4 of the Act, and its                      accumulation of fine sediments, the loss
                                               to moderate decrease in water flow we                   implementing regulations at 50 CFR part               of flowing water, and impairment of
                                               still expect abundance to be maintained                 424, set forth the procedures for adding              water quality, all of which are
                                               at moderate levels. Overall, the Rio                    species to the Federal Lists of                       exacerbated by the effects of climate
                                               Grande—Lower Canyons population                         Endangered and Threatened Wildlife                    change. Predation (Factor C) is also
                                               exhibits moderate resiliency.                           and Plants. Under section 4(b)(1)(a), the             affecting those populations already
                                                  Rio Grande—Laredo: Similar to the                    Secretary is to make endangered or                    experiencing low stream flow, and
                                               Lower Canyons population, the Laredo                    threatened determinations required by                 barriers to fish movement (Factor E)
                                               population has numerous mussel beds                     subsection 4(a)(1) solely on the basis of             prevent recolonization after stochastic
                                               with high Texas hornshell abundance                     the best scientific and commercial data               events.
                                               and evidence of reproduction. However,                  available to her after conducting a                      The Texas hornshell has declined
                                               drought and upstream water                              review of the status of the species and               significantly in overall distribution and
                                               management will continue to reduce                      after taking into account conservation                abundance, with the species currently
                                               flows in the Rio Grande. Water quality                  efforts by States or foreign nations. The             occupying approximately 15 percent of
                                               will continue to decrease due to lower                  standards for determining whether a                   its historical range in the United States.
                                               flows, and fine sediments will                          species is endangered or threatened are               Between one-half and two-thirds of the
                                               accumulate. Declining water flow will                   provided in section 3 of the Act. An                  Texas hornshell’s historical range
                                               cause fine sediments to accumulate and                  endangered species is any species that                occurred in Mexico; we have very low
                                               water quality to decline, leading to a                  is ‘‘in danger of extinction throughout               confidence in the species’ current
                                               decline in population abundance.                        all or a significant portion of its range.’’          condition throughout most of the
                                               Overall, the Rio Grande—Laredo has                      A threatened species is any species that              Mexican range. The resulting remnant
                                               moderate resiliency.                                    is ‘‘likely to become an endangered                   populations occupy shorter reaches
                                                  Mexico: We have low confidence in                    species within the foreseeable future                 compared to presumed historical
                                               the species’ current condition                          throughout all or a significant portion of            populations, and they are all isolated
                                               throughout most of the Mexican range.                   its range.’’ Per section 4(a)(1) of the Act,          from one another.
                                               One or more of these populations may                    in reviewing the status of the species to                The primary historical reason for this
                                               still be extant, or they may all be                     determine if it meets the definition of               reduction in range was reservoir
                                               extirpated. We have no recent data on                   endangered or of threatened, we                       construction and unsuitable water
                                               the species’ occurrence in Mexico; the                  determine whether any species is an                   quality. Large reservoirs have been
                                               last live recordings are from the mid-                  endangered species or a threatened                    constructed on the Rio Grande and
                                               1980s. Because of this uncertainty, we                  species because of any of the following               Pecos River, and much of the Pecos
                                               did not rely on the Texas hornshell’s                   five factors: (A) The present or                      River upstream of the confluence with
                                               distribution in Mexico when evaluating                  threatened destruction, modification, or              Independence Creek now has salinity
                                               the viability of the species.                           curtailment of its habitat or range; (B)              levels too high for mussel habitation
                                                                                                       overutilization for commercial,                       (Hoagstrom 2009, p. 28). The effects of
                                               Future Condition
                                                                                                       recreational, scientific, or educational              these reservoirs extend beyond
                                                 As part of the SSA, we also developed                 purposes; (C) disease or predation; (D)               fragmentation of populations; the
                                               multiple future condition scenarios to                  the inadequacy of existing regulatory                 resultant downstream water releases do
                                               capture the range of uncertainties                      mechanisms; and (E) other natural or                  not mimic natural flow regimes, and the
                                               regarding future threats and the                        manmade factors affecting its continued               change in timing and frequency of
                                               projected responses by the Texas                        existence. Listing actions may be                     cleansing flows results in increases in
                                               hornshell. Our scenarios included a                     warranted based on any of the above                   fine sediments, increases in predation,
                                               status quo scenario, which incorporated                 threat factors, singly or in combination.             and decreases in water quality. Add to
                                               the current risk factors continuing on                     The fundamental question before the                this the exacerbating effects of climate
                                               the same trajectory that they are on now.               Service is whether the species warrants               change—increased temperature and
                                               We also evaluated four additional future                protection as an endangered or                        decreased stream flow—and the
                                               scenarios that incorporated varying                     threatened species under the Act. To                  remaining Texas hornshell populations
                                               levels of increasing risk factors with                  make this determination, we evaluated                 face moderate to high levels of risk of
                                               elevated negative effects on hornshell                  extinction risk, described in terms of the            extirpation currently. For the
                                               populations. However, because we                        current condition of populations and                  populations occupying the smaller
                                               determined that the current condition of                their distribution (taking into account               reaches (such as the Black River, Devils
                                               the Texas hornshell and the associated                  the risk factors (i.e., threats, stressors)           River, and Pecos River populations), a
                                               status quo projections were consistent                  and their effects on those populations).              single stochastic event such as
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                                               with an endangered species (see                         For any species, as population                        contaminant spill or drought could
                                               Determination, below), we are not                       conditions decline and distribution                   eliminate an entire population of Texas
                                               presenting the results of the other future              shrinks, the species’ overall viability               hornshell. These effects are heightened
                                               scenarios in this proposed rule. The                    declines and extinction risk increases.               at the species level because the isolation
                                               additional future scenarios project                        We have carefully assessed the best                of the populations prohibits natural
                                               conditions that are worse for the Texas                 scientific and commercial information                 recolonization from host fish carrying
                                               hornshell. Since the status quo scenario                available regarding the past, present,                Texas hornshell glochidia, which likely


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                                               52806               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               happened in the past and allowed for                       The Act defines an endangered                      agencies; private organizations; and
                                               the species to ebb and flow from                        species as any species that is ‘‘in danger            individuals. The Act encourages
                                               suitable areas.                                         of extinction throughout all or a                     cooperation with the States and other
                                                  Populations in both large and small                  significant portion of its range’’ and a              countries and calls for recovery actions
                                               reaches face risks from natural and                     threatened species as any species ‘‘that              to be carried out for listed species. The
                                               anthropogenic sources. Climate change                   is likely to become endangered                        protection required by Federal agencies
                                               has already begun to affect the regions                 throughout all or a significant portion of            and the prohibitions against certain
                                               of Texas and New Mexico where Texas                     its range within the foreseeable future.’’            activities are discussed, in part, below.
                                               hornshell occurs, resulting in higher air               We find that the Texas hornshell is                      The primary purpose of the Act is the
                                               temperatures, increased evaporation,                    presently in danger of extinction                     conservation of endangered and
                                               increased groundwater pumping, and                      throughout its entire range based on the              threatened species and the ecosystems
                                               changing precipitation patterns such                    severity and immediacy of threats                     upon which they depend. The ultimate
                                               that water levels rangewide have                        currently impacting the species. The                  goal of such conservation efforts is the
                                               already reached historic lows. These                    overall range has been significantly                  recovery of these listed species, so that
                                               low water levels put the populations at                 reduced, and the remaining habitat and                they no longer need the protective
                                               risk of habitat loss from increased fine                populations are threatened by a                       measures of the Act. Subsection 4(f) of
                                               sediments, poor water quality, and                      multitude of factors acting in                        the Act calls for the Service to develop
                                               increased predation risk.                               combination to reduce the overall                     and implement recovery plans for the
                                                  These risks, alone or in combination,                viability of the species. The risk of                 conservation of endangered and
                                               are expected to result in the extirpation               extinction is high because the remaining              threatened species. The recovery
                                               of additional populations, further                      populations have a high risk of                       planning process involves the
                                               reducing the overall redundancy and                     extirpation, are isolated, and have                   identification of actions that are
                                               representation of the species.                          limited potential for recolonization.                 necessary to halt or reverse the species’
                                               Historically, the species, with a large                 Therefore, on the basis of the best                   decline by addressing the threats to its
                                               range of interconnected populations,                    available scientific and commercial                   survival and recovery. The goal of this
                                               would have been resilient to stochastic                 information, we propose listing the                   process is to restore listed species to a
                                               events such as drought and                              Texas hornshell as endangered in                      point where they are secure, self-
                                               sedimentation because even if some                      accordance with sections 3(6) and                     sustaining, and functioning components
                                               populations were extirpated by such                     4(a)(1) of the Act. We find that a                    of their ecosystems.
                                               events, they could be recolonized over                  threatened species status is not                         Recovery planning includes the
                                               time by dispersal from nearby surviving                 appropriate for the Texas hornshell                   development of a recovery outline
                                               populations. This connectivity would                    because of the currently contracted                   shortly after a species is listed and
                                               have made for a highly resilient species                range (loss of 85 percent of its historic             preparation of a draft and final recovery
                                               overall. However, under current                         range in the United States, and likely                plan. The recovery outline guides the
                                               conditions, connectivity is prevented                   more in Mexico), because the threats are              immediate implementation of urgent
                                               due to large reservoirs and unsuitably                  occurring across the entire range of the              recovery actions and describes the
                                               high salinity levels between                            species, and because the threats are                  process to be used to develop a recovery
                                               populations. As a consequence of these                  ongoing currently and are expected to                 plan. Revisions of the plan may be done
                                               current conditions, the viability of the                continue or worsen into the future.                   to address continuing or new threats to
                                               Texas hornshell now primarily depends                   Because the species is already in danger              the species, as new substantive
                                               on maintaining the remaining isolated                   of extinction throughout its range, a                 information becomes available. The
                                               populations.                                            threatened status is not appropriate.                 recovery plan also identifies recovery
                                                  Of the five remaining isolated                          Under the Act and our implementing                 criteria for review of when a species
                                               populations, three are small in                         regulations, a species may warrant                    may be ready for downlisting or
                                               abundance and occupied stream length                    listing if it is endangered or threatened             delisting, and methods for monitoring
                                               and have low to no resiliency. The                      throughout all or a significant portion of            recovery progress. Recovery plans also
                                               remaining two are larger, with increased                its range. Because we have determined                 establish a framework for agencies to
                                               abundance and occupied stream length;                   that the Texas hornshell is endangered                coordinate their recovery efforts and
                                               however, flow reduction, water quality                  throughout all of its range, no portion of            provide estimates of the cost of
                                               decline, and habitat loss from                          its range can be ‘‘significant’’ for                  implementing recovery tasks. Recovery
                                               sedimentation reduce the abundance                      purposes of the definitions of                        teams (composed of species experts,
                                               and distribution of those populations.                  ‘‘endangered species’’ and ‘‘threatened               Federal and State agencies,
                                               We have no information on population                    species.’’ See the Final Policy on                    nongovernmental organizations, and
                                               status in Mexico. Therefore, the Texas                  Interpretation of the Phrase ‘‘Significant            stakeholders) are often established to
                                               hornshell has no populations that are                   Portion of Its Range’’ in the Endangered              develop recovery plans. When
                                               currently considered highly resilient.                  Species Act’s Definitions of                          completed, the recovery outline, draft
                                               The high risk of extirpation of these                   ‘‘Endangered Species’’ and ‘‘Threatened               recovery plan, and the final recovery
                                               populations leads to low levels of                      Species’’ (79 FR 37578; July 1, 2014).                plan will be available on our Web site
                                               redundancy (few populations will                                                                              (http://www.fws.gov/endangered), or
                                               persist to withstand catastrophic events)               Available Conservation Measures                       from our Texas Coastal Ecological
                                               and representation (little to no                          Conservation measures provided to                   Services Field Office (see FOR FURTHER
                                               ecological or genetic diversity will                    species listed as endangered or                       INFORMATION CONTACT).
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                                               persist to respond to changing                          threatened species under the Act                        Implementation of recovery actions
                                               environmental conditions). Overall,                     include recognition, recovery actions,                generally requires the participation of a
                                               these low levels of resiliency,                         requirements for Federal protection, and              broad range of partners, including other
                                               redundancy, and representation result                   prohibitions against certain practices.               Federal agencies, States, Tribes,
                                               in the Texas hornshell having low                       Recognition through listing results in                nongovernmental organizations,
                                               viability, and the species currently faces              public awareness, and conservation by                 businesses, and private landowners.
                                               a high risk of extinction.                              Federal, State, Tribal, and local                     Examples of recovery actions include


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                                                                   Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                           52807

                                               habitat restoration (e.g., restoration of               described in the preceding paragraph                  with existing regulations and permit
                                               native vegetation), research, captive                   include management and any other                      requirements; this list is not
                                               propagation and reintroduction, and                     landscape-altering activities on Federal              comprehensive:
                                               outreach and education. The recovery of                 lands administered by the Bureau of                      (1) Normal agricultural and
                                               many listed species cannot be                           Land Management, Bureau of                            silvicultural practices, including
                                               accomplished solely on Federal lands                    Reclamation, and National Park Service;               herbicide and pesticide use, which are
                                               because their ranges may occur                          issuance of section 404 Clean Water Act               carried out in accordance with any
                                               primarily or solely on non-Federal                      (33 U.S.C. 1251 et seq.) permits by the               existing regulations, permit and label
                                               lands. To achieve recovery of these                     U.S. Army Corps of Engineers; and                     requirements, and best management
                                               species requires cooperative                            construction and maintenance of roads                 practices; and
                                               conservation efforts on private, State,                 or highways by the Federal Highway                       (2) Normal residential landscape
                                               and Tribal lands. If this species is listed,            Administration.                                       activities.
                                               funding for recovery actions will be                       The Act and its implementing                          Based on the best available
                                               available from a variety of sources,                    regulations set forth a series of general             information, if we list this species, the
                                               including Federal budgets, State                        prohibitions and exceptions that apply                following activities may potentially
                                               programs, and cost share grants for non-                to endangered wildlife. The prohibitions              result in a violation of section 9 of the
                                               Federal landowners, the academic                        of section 9(a)(1) of the Act, codified at            Act; this list is not comprehensive:
                                               community, and nongovernmental                          50 CFR 17.21, make it illegal for any                    (1) Unauthorized handling or
                                               organizations. In addition, pursuant to                 person subject to the jurisdiction of the             collecting of the species;
                                               section 6 of the Act, the States of Texas               United States to take (which includes                    (2) Modification of the channel or
                                               and New Mexico would be eligible for                    harass, harm, pursue, hunt, shoot,                    water flow of any stream in which the
                                               Federal funds to implement                              wound, kill, trap, capture, or collect; or            Texas hornshell is known to occur;
                                               management actions that promote the                     to attempt any of these) endangered                      (3) Livestock grazing that results in
                                               protection or recovery of the Texas                     wildlife within the United States or on               direct or indirect destruction of stream
                                               hornshell. Information on our grant                     the high seas. In addition, it is unlawful            habitat; and
                                               programs that are available to aid                      to import; export; deliver, receive, carry,              (4) Discharge of chemicals or fill
                                               species recovery can be found at: http://               transport, or ship in interstate or foreign           material into any waters in which the
                                               www.fws.gov/grants.                                     commerce in the course of commercial                  Texas hornshell is known to occur.
                                                  Although the Texas hornshell is only                 activity; or sell or offer for sale in                   Questions regarding whether specific
                                               proposed for listing under the Act at                   interstate or foreign commerce any                    activities would constitute a violation of
                                               this time, please let us know if you are                listed species. It is also illegal to                 section 9 of the Act should be directed
                                               interested in participating in recovery                 possess, sell, deliver, carry, transport, or          to the Texas Coastal Ecological Services
                                               efforts for this species. Additionally, we              ship any such wildlife that has been                  Field Office (see FOR FURTHER
                                               invite you to submit any new                            taken illegally. Certain exceptions apply             INFORMATION CONTACT).
                                               information on this species whenever it                 to employees of the Service, the
                                               becomes available and any information                   National Marine Fisheries Service, other              Critical Habitat for the Texas Hornshell
                                               you may have for recovery planning                      Federal land management agencies, and                 Background
                                               purposes (see FOR FURTHER INFORMATION                   State conservation agencies.
                                               CONTACT).                                                  We may issue permits to carry out                    Critical habitat is defined in section 3
                                                  Section 7(a) of the Act requires                     otherwise prohibited activities                       of the Act as:
                                               Federal agencies to evaluate their                      involving endangered wildlife under                     (1) The specific areas within the
                                               actions with respect to any species that                certain circumstances. Regulations                    geographical area occupied by the
                                               is proposed or listed as an endangered                  governing permits are codified at 50                  species, at the time it is listed in
                                               or threatened species and with respect                  CFR 17.22. With regard to endangered                  accordance with the Act, on which are
                                               to its critical habitat, if any is                      wildlife, a permit may be issued for the              found those physical or biological
                                               designated. Regulations implementing                    following purposes: For scientific                    features:
                                               this interagency cooperation provision                  purposes, to enhance the propagation or                 (a) Essential to the conservation of the
                                               of the Act are codified at 50 CFR part                  survival of the species, and for                      species, and
                                               402. Section 7(a)(4) of the Act requires                incidental take in connection with                      (b) Which may require special
                                               Federal agencies to confer with the                     otherwise lawful activities. There are                management considerations or
                                               Service on any action that is likely to                 also certain statutory exemptions from                protection; and
                                               jeopardize the continued existence of a                 the prohibitions, which are found in                    (2) Specific areas outside the
                                               species proposed for listing or result in               sections 9 and 10 of the Act.                         geographical area occupied by the
                                               destruction or adverse modification of                     It is our policy, as published in the              species at the time it is listed, upon a
                                               proposed critical habitat. If a species is              Federal Register on July 1, 1994 (59 FR               determination that such areas are
                                               listed subsequently, section 7(a)(2) of                 34272), to identify to the maximum                    essential for the conservation of the
                                               the Act requires Federal agencies to                    extent practicable at the time a species              species.
                                               ensure that activities they authorize,                  is listed, those activities that would or               Conservation, as defined under
                                               fund, or carry out are not likely to                    would not constitute a violation of                   section 3 of the Act, means to use and
                                               jeopardize the continued existence of                   section 9 of the Act. The intent of this              the use of all methods and procedures
                                               the species or destroy or adversely                     policy is to increase public awareness of             that are necessary to bring an
                                               modify its critical habitat. If a Federal               the effect of a proposed listing on                   endangered or threatened species to the
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                                               action may affect a listed species or its               proposed and ongoing activities within                point at which the measures provided
                                               critical habitat, the responsible Federal               the range of the species proposed for                 pursuant to the Act are no longer
                                               agency must enter into consultation                     listing. Based on the best available                  necessary. Such methods and
                                               with the Service.                                       information, if we list this species, the             procedures include, but are not limited
                                                  Federal agency actions within the                    following actions are unlikely to result              to, all activities associated with
                                               species’ habitat that may require                       in a violation of section 9, if these                 scientific resources management such as
                                               conference or consultation or both as                   activities are carried out in accordance              research, census, law enforcement,


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                                               52808               Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules

                                               habitat acquisition and maintenance,                    determined to be endangered or                        updated occurrence records for the
                                               propagation, live trapping, and                         threatened. Our regulations (50 CFR                   Texas hornshell, future climate change
                                               transplantation, and, in the                            424.12(a)(1)) state that the designation              effects on the species’ habitat, and other
                                               extraordinary case where population                     of critical habitat is not prudent when               analyses. Therefore, we conclude that
                                               pressures within a given ecosystem                      one or both of the following situations               the designation of critical habitat is not
                                               cannot be otherwise relieved, may                       exist: (1) The species is threatened by               determinable for the Texas hornshell at
                                               include regulated taking.                               taking or other human activity, and                   this time. We will make a determination
                                                  Critical habitat receives protection                 identification of critical habitat can be             on critical habitat no later than 1 year
                                               under section 7 of the Act through the                  expected to increase the degree of threat             following any final listing
                                               requirement that Federal agencies                       to the species, or (2) such designation of            determination.
                                               ensure, in consultation with the Service,               critical habitat would not be beneficial
                                               that any action they authorize, fund, or                to the species.                                       Required Determinations
                                               carry out is not likely to result in the                   There is currently no imminent threat              Clarity of the Rule
                                               destruction or adverse modification of                  of take attributed to collection or
                                               critical habitat. The designation of                    vandalism under Factor B for the Texas                   We are required by Executive Orders
                                               critical habitat does not affect land                   hornshell, and identification and                     12866 and 12988 and by the
                                               ownership or establish a refuge,                        mapping of critical habitat is not likely             Presidential Memorandum of June 1,
                                               wilderness, reserve, preserve, or other                 to increase any such threat. In the                   1998, to write all rules in plain
                                               conservation area. Such designation                     absence of finding that the designation               language. This means that each rule we
                                               does not allow the government or public                 of critical habitat would increase threats            publish must:
                                               to access private lands. Such                           to a species, if there are any benefits to               (1) Be logically organized;
                                               designation does not require                            a critical habitat designation, then a                   (2) Use the active voice to address
                                               implementation of restoration, recovery,                prudent finding is warranted. The                     readers directly;
                                               or enhancement measures by non-                         potential benefits of designation
                                               Federal landowners. Where a landowner                   include: (1) Triggering consultation                     (3) Use clear language rather than
                                               requests Federal agency funding or                      under section 7 of the Act in new areas               jargon;
                                               authorization for an action that may                    for actions in which there may be a                      (4) Be divided into short sections and
                                               affect a listed species or critical habitat,            Federal nexus where it would not                      sentences; and
                                               the consultation requirements of section                otherwise occur because, for example, it                 (5) Use lists and tables wherever
                                               7(a)(2) of the Act would apply, but even                is or has become unoccupied or the                    possible.
                                               in the event of a destruction or adverse                occupancy is in question; (2) focusing                   If you feel that we have not met these
                                               modification finding, the obligation of                 conservation activities on the most                   requirements, send us comments by one
                                               the Federal action agency and the                       essential features and areas; (3)                     of the methods listed in ADDRESSES. To
                                               landowner is not to restore or recover                  providing educational benefits to State               better help us revise the rule, your
                                               the species, but to implement                           or county governments or private                      comments should be as specific as
                                               reasonable and prudent alternatives to                  entities; and (4) preventing people from              possible. For example, you should tell
                                               avoid destruction or adverse                            causing inadvertent harm to the species.              us the numbers of the sections or
                                               modification of critical habitat.                       Therefore, because we have determined                 paragraphs that are unclearly written,
                                                  Section 4 of the Act requires that we                that the designation of critical habitat              which sections or sentences are too
                                               designate critical habitat on the basis of              will not likely increase the degree of                long, the sections where you feel lists or
                                               the best scientific data available.                     threat to these species and may provide               tables would be useful, etc.
                                               Further, our Policy on Information                      some measure of benefit, we find that
                                               Standards Under the Endangered                          designation of critical habitat is prudent            National Environmental Policy Act (42
                                               Species Act (published in the Federal                   for the Texas hornshell.                              U.S.C. 4321 et seq.)
                                               Register on July 1, 1994 (59 FR 34271)),
                                               the Information Quality Act (section 515                Critical Habitat Determinability                         We have determined that
                                               of the Treasury and General                                Having determined that designation is              environmental assessments and
                                               Government Appropriations Act for                       prudent, under section 4(a)(3) of the Act             environmental impact statements, as
                                               Fiscal Year 2001 (Pub. L. 106–554; H.R.                 we must find whether critical habitat for             defined under the authority of the
                                               5658)), and our associated Information                  the species is determinable. Our                      National Environmental Policy Act
                                               Quality Guidelines, provide criteria,                   regulations at 50 CFR 424.12(a)(2) state              (NEPA; 42 U.S.C. 4321 et seq.), need not
                                               establish procedures, and provide                       that critical habitat is not determinable             be prepared in connection with listing
                                               guidance to ensure that our decisions                   when one or both of the following                     a species as an endangered or
                                               are based on the best scientific data                   situations exist: (1) Information                     threatened species under the
                                               available. They require our biologists, to              sufficient to perform required analyses               Endangered Species Act. We published
                                               the extent consistent with the Act and                  of the impacts of the designation is                  a notice outlining our reasons for this
                                               with the use of the best scientific data                lacking, or (2) the biological needs of the           determination in the Federal Register
                                               available, to use primary and original                  species are not sufficiently well known               on October 25, 1983 (48 FR 49244).
                                               sources of information as the basis for                 to permit identification of an area as                References Cited
                                               recommendations to designate critical                   critical habitat.
                                               habitat.                                                   As discussed above, we have                          A complete list of references cited is
                                                                                                       reviewed the available information                    available in Appendix A of the SSA
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                                               Prudency Determination                                  pertaining to the biological needs of this            Report (U.S. Fish and Wildlife Service.
                                                 Section 4(a)(3) of the Act, as                        species and habitat characteristics                   2016. Species status assessment report
                                               amended, and implementing regulations                   where this species is located. Because                for the Texas hornshell (Popenaias
                                               (50 CFR 424.12), require that, to the                   the biological needs are not sufficiently             popeii), Version 1.0. Albuquerque, NM),
                                               maximum extent prudent and                              well known to permit identification of                available online at http://
                                               determinable, the Secretary designate                   critical habitat, we are seeking                      www.regulations.gov, under Docket
                                               critical habitat at the time the species is             additional information regarding                      Number FWS–R2–ES–2016–0077.


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                                                                      Federal Register / Vol. 81, No. 154 / Wednesday, August 10, 2016 / Proposed Rules                                                                52809

                                               Authors                                                        Proposed Regulation Promulgation                              Authority: 16 U.S.C. 1361–1407; 1531–
                                                                                                                                                                          1544; and 4201–4245, unless otherwise
                                                 The primary authors of this proposed                           Accordingly, we propose to amend                          noted.
                                               rule are the staff members of the Texas                        part 17, subchapter B of chapter I, title                   ■ 2. Amend § 17.11(h) by adding an
                                               Coastal Ecological Services Field Office.                      50 of the Code of Federal Regulations,                      entry for ‘‘Hornshell, Texas’’ to the List
                                                                                                              as set forth below:                                         of Endangered and Threatened Wildlife
                                               List of Subjects in 50 CFR Part 17
                                                                                                                                                                          in alphabetical order under Clams:
                                                 Endangered and threatened species,                           PART 17—ENDANGERED AND
                                                                                                              THREATENED WILDLIFE AND PLANTS                              § 17.11 Endangered and threatened
                                               Exports, Imports, Reporting and
                                                                                                                                                                          wildlife.
                                               recordkeeping requirements,
                                               Transportation.                                                ■ 1. The authority citation for part 17                     *       *    *          *     *
                                                                                                              continues to read as follows:                                   (h) * * *

                                                                                                                                                                                              Listing citations and applicable
                                                         Common name                                    Scientific name                            Where listed                  Status                      rules


                                                          *                         *                             *                       *                         *                         *                    *
                                                                CLAMS

                                                        *                           *                      *                             *                       *                             *                   *
                                               Hornshell, Texas ........................     Popenaias popeii ......................   Wherever found ........................   E            [Federal Register citation
                                                                                                                                                                                                 when published as a final
                                                                                                                                                                                                 rule.]

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                                                 Dated: July 21, 2016.
                                               Stephen Guertin,
                                               Acting Director, U.S. Fish and Wildlife
                                               Service.
                                               [FR Doc. 2016–18816 Filed 8–9–16; 8:45 am]
                                               BILLING CODE P
Lhorne on DSK30JT082PROD with PROPOSALS




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Document Created: 2016-08-10 01:59:17
Document Modified: 2016-08-10 01:59:17
CategoryRegulatory Information
CollectionFederal Register
sudoc ClassAE 2.7:
GS 4.107:
AE 2.106:
PublisherOffice of the Federal Register, National Archives and Records Administration
SectionProposed Rules
ActionProposed rule.
DatesWe will accept comments received or postmarked on or before October 11, 2016. Comments submitted electronically using the Federal
ContactChuck Ardizzone, U.S. Fish and Wildlife Service, Texas Coastal Ecological Services Field Office, 17629 El Camino Real #211, Houston, TX 77058; by telephone 281-286-8282; or by facsimile 281-488-5882. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339.
FR Citation81 FR 52796 
RIN Number1018-BB34
CFR AssociatedEndangered and Threatened Species; Exports; Imports; Reporting and Recordkeeping Requirements and Transportation

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